| J.K. Wipff |
Plants annual, perennial, or of indefinite
duration. Culms 5-250 cm, erect or decumbent, branching basally or at
aerial culm nodes, when annual or of indefinite duration usually decumbent and
rooting at the lower nodes. Sheaths open; ligules membranous,
sometimes ciliate; blades usually flat. Inflorescences terminal,
sometimes also axillary, usually panicles of 1-sided spikelike branches (sometimes
only 1 branch) attached digitately or racemosely to a rachis, sometimes simple
panicles of solitary, pedicellate spikelets; spikelike branches, if present,
sometimes with secondary branches, primary branch axes triquetrous, bearing
spikelets abaxially, in 2 rows, usually in unequally pedicellate groups of 2-5,
occasionally borne singly. Spikelets 1.2-8.2 mm, lanceoloid to ellipsoid,
dorsally compressed, apices obtuse to acuminate, unawned, with 2 florets; disarticulation
beneath the glumes. Lower glumes absent or to 1/4 as long as the spikelets;
upper glumes usually from 1/6 as long as to equaling the spikelets, occasionally
absent, 0-5-veined, usually pubescent; lower florets sterile; lower
lemmas membranous, usually as long as the upper lemmas, usually pubescent,
(3)5-7(13)-veined; lower paleas absent or reduced; upper lemmas
mostly stiffly chartaceous to cartilaginous, obscurely veined, with 0.5-1 mm
hyaline margins that embrace the upper paleas; upper paleas similar to
the upper lemmas in texture and size; lodicules 3, cuneate; anthers
3. Caryopses plano-convex; embryos 1/5-1/2 as long as the caryopses;
hila punctiform to ellipsoid. x = 9. Name from the Latin digitus,
finger, a reference to the digitate inflorescence of some species.
Digitaria has approximately 200 species and grows primarily in tropical
and warm-temperate regions, often in disturbed, open sites. Some species are
grown as cereals; others for forage or as lawn grasses. In North America, the
genus is best known for two of its weedy species, D.
sanguinalis and D. ciliaris.
There are 29 species known to occur in the Flora region; 18 are native
to the region.
Most annual species of Digitaria will survive several
years in regions without a pronounced cold season; such species are described
as being of indefinite duration.
NOTE: The pubescence of the lower lemmas may be mistaken for two white lines between the veins because the individual hairs are not visible, being both tightly packed and closely appressed.
1 |
Inflorescences
simple open panicles, with well-developed primary and secondary branches;
branches and pedicels divergent; spikelets solitary (2) |
Inflorescences panicles of spikelike
branches; secondary branches rarely present; spikelets appressed to the
branches, in groups of 2-5 on the middle portion of the primary branches
(5) |
|
Upper glumes absent or
to 0.6 mm long, veinless ..... 4. D.
tomentosa |
|
Upper glumes 1.8-3.8 mm long, 3-7-veined
(3) |
|
Spikelets 3.5-4.6 mm
long; upper glumes 5-7-veined ..... 1. D.
arenicola |
|
Spikelets 2.2-3.3 mm long; upper glumes
3(5)-veined (4) |
|
Lower lemmas 7-veined,
veins not equally spaced ..... 2. D. cognata |
|
Lower lemmas 5-veined, veins equidistant ..... 3.
D. pubiflora |
|
Spikelets in groups of
3-5 on the middle portions of the primary branches, the longer pedicels
in each group often adnate to the branch axes for part of their length
(6) |
|
Spikelets paired on the middle portions
of the primary branches; pedicels not adnate to the branch axes (17) |
|
Upper lemmas pale yellow
or gray when immature, light brown to brown when mature, sometimes purple-tinged
(7) |
|
Upper lemmas brown when immature, becoming
dark brown when mature (9) |
|
Upper glumes 1/6-1/3
long as the spikelets; sheaths and blades pubescent ..... 13.
D. serotina |
|
Upper glumes equaling or almost equaling
the spikelets; sheaths and blades usually glabrous (8) |
|
Upper glumes 5-veined;
spikelets elliptic to obovate; plants stoloniferous ..... 14.
D. longiflora |
|
Upper glumes 3-veined; spikelets lanceolate;
plants not stoloniferous ..... 15. D.
floridana |
|
Primary panicle branches
wing-margined, the wings at least 1/2 as wide as the midribs (10) |
|
Primary panicle branches not wing-margined
or the wings not as wide as the midribs (12) |
|
Plants
always with axillary panicles in the lower leaf sheaths, these panicles
sometimes completely concealed by the sheaths; spikelets 1.7-2.3 mm long ..... 16.
D. ischaemum |
|
Plants without axillary panicles; spikelets
1.2-1.7 mm long (11) |
|
Primary panicle branches,
if more than 2, racemose, the terminal branches erect, the other branches
usually divergent; upper lemmas light brown to brown at maturity; upper
glumes almost as long as the upper lemmas ..... 15. D.
floridana |
|
Primary panicle branches usually all
digitate, sometimes 1 below the others, all the branches erect to ascending;
upper lemmas dark brown at maturity; upper glumes 1/2 as long as to almost
equaling the upper lemmas ..... 17. D.
violascens |
|
Lower lemmas pubescent
(13) |
|
Lower lemmas glabrous (15) |
|
Plants annual, or short-lived
perennials, branching at the lower nodes; cauline nodes 3-6 ..... 7.
D. filiformis |
|
Plants perennial, not branching at the
lower nodes; cauline nodes 1-2 (14) |
|
Upper glumes and lower
lemmas with long, glandular-tipped hairs along their margins and intercostal
regions ..... 8. D. leucocoma |
|
Upper glumes and lower lemmas glabrous
over most of their length, sparsely pubescent near the apices, the hairs
short, not glandular-tipped ..... 6. D.
bakeri |
|
Upper glumes less than
1/2 as long as the spikelets ..... 5. D.
gracillima |
|
Upper glumes more than 1/2 as long
as the spikelets (16) |
|
Plants annual, branching
at the lower nodes; culm nodes 3-6; upper glumes obtuse ..... 7.
D. filiformis |
|
Plants perennial, not branching at the
lower nodes; culm nodes 1-2; upper glumes acute ..... 6. D.
bakeri |
|
Upper lemmas brown when
immature, almost always dark brown when mature; primary branches not wing-margined
or with wings less than 1/2 as wide as the midribs (18) |
|
Upper lemmas pale yellow, tan, or gray,
sometimes purple-tinged, when immature; gray, yellow, tan, light brown,
or purple at maturity; primary branches sometimes wing-margined, the margin
widths various (23) |
|
Spikelets (including
pubescence) 1.3-3.1 mm long; lower lemmas (including pubescence) shorter
than or no more than 0.5 mm longer than the upper florets; ligules 0.1-1.5
mm long, ciliate; lower lemmas sparsely to densely pubescent, the hairs
less than 1 mm long, appressed, not spreading at maturity (19) |
|
Spikelets (including pubescence) 3.7-7.5
mm long; lower lemmas (including pubescence) exceeding the upper florets
by 0.8 mm or more; ligules 1-6 mm long, not ciliate; lower lemmas densely
pubescent, the hairs 1-6 mm long, usually spreading at maturity (21) |
|
Lower glumes 0.3-1 mm
long; plants perennial, with hard, knotty, shortly rhizomatous bases;
culms erect, not rooting at the lower nodes; lower lemmas 5-veined, the
veins equally spaced ..... 9. D.
hitchcockii |
|
Lower glumes absent or to 0.1 mm long;
plants annual, or short-lived perennials; culms erect or decumbent, sometimes
rooting at the lower nodes; lower lemmas 5-7-veined, the veins unequally
spaced, the outer veins closely spaced (20) |
|
Upper lemmas dark brown
at maturity; lower primary panicle branches without secondary branches;
upper glumes with clavate to capitate hairs ..... 7. D.
filiformis |
|
Upper lemmas usually gray, sometimes
brown, at maturity; lower primary panicle branches with strongly divergent
secondary branches; upper glumes with tapering or parallel-sided hairs ..... 25.
D. velutina |
|
Terminal pedicels of
primary branches 7.4-20 mm long; primary branches usually divergent, sometimes
ascending, at maturity, the middle internodes (4.5)6-15 mm long ..... 10.
D. patens |
|
Terminal pedicels of primary branches
1.7-6(7) mm long; primary branches appressed to ascending at maturity,
the middle internodes 2-6 mm long (22) |
|
Lower lemmas pubescent
between most, sometimes all, of the veins and on the margins ..... 12.
D. insularis |
|
Lower lemmas glabrous between the veins,
pubescent on the margins, sometimes also on the lateral veins ..... 11.
D. californica |
|
Primary panicle branches
not or only narrowly wing-margined, the wings no more than 1/2 as wide
as the midribs (24) |
|
Primary branches winged, the wings at
least 1/2 wide as the midribs (28) |
|
Spikelets 1.5-2.5 mm
long (25) |
|
Spikelets 2.5-3.6 mm long (26) |
|
Upper glumes glabrous;
plants rhizomatous; culms decumbent but usually not rooting at the lower
nodes ..... 18. D. abyssinica |
|
Upper glumes shortly villous on the margins,
sometimes also elsewhere; plants not rhizomatous; culms erect or decumbent
and rooting at the lower nodes ..... 21. D.
texana |
|
Culms usually branching
at the aerial nodes, not rooting at the lower nodes; leaf blades 2-2.2
mm wide, flat or folded; upper glumes glabrous ..... 19. D.
pauciflora |
|
Culms not branching at the aerial nodes,
often rooting at the lower nodes; leaf blades 2-7mm wide, flat; upper
glumes villous or glabrous (27) |
|
Upper glumes 7-9-veined,
glabrous or obscurely pubescent; plants of indefinite duration ..... 20.
D. simpsonii |
|
Upper glumes (3)5-veined, shortly villous
on the margins and sometimes between the margins; plants perennial ..... 21.
D. texana |
|
Plants perennial, usually
stoloniferous, sometimes also rhizomatous (29) |
|
Plants annual or of indefinite duration,
usually neither rhizomatous nor stoloniferous (31) |
|
Leaf blades 1-3 mm wide;
panicles with 2-4 primary branches, the branches 2-7 cm long ..... 22.
D. didactyla |
|
Leaf blades 3-13 mm wide; panicles with
2-18 primary branches, the branches 5-25 cm long (30) |
|
Midveins of the lower
lemmas scabrous, at least on the distal 1/2 ..... 24. D.
milanjiana |
|
Midveins of the lower lemmas smooth
throughout ..... 23. D. eriantha |
|
Lateral veins of the
lower lemmas scabrous for the distal 2/3 of their length, sometimes scabrous
throughout (use 20× magnification); leaf blades usually with papillose-based
hairs on both surfaces ..... 28. D.
sanguinalis |
|
Lateral veins of the lower lemmas smooth
throughout or scabrous only on the distal 1/3; leaf blades with or without
papillose-based hairs (32) |
|
Lower lemmas of the
lower spikelets of each pair 7-veined, the 2 lateral veins on each side
crowded together near the margins, the 3 central veins equally spaced
(33) |
|
Lower lemmas of the lower spikelets of
each pair 5- or 7-veined, the 2 or 3 lateral veins on each side crowded
together near the margins, well-separated from the midvein (36) |
|
Lower primary panicle
branches with strongly divergent secondary branches ..... 25. D.
velutina |
|
Lower primary panicle branches without
secondary branches (34) |
|
Spikelets 2.6-3.7 mm
long; spikelets dimorphic with respect to their pubescence; lower lemmas
of the upper spikelets of each spikelet pair with marginal hairs that
become widely divergent at maturity; lower lemmas of the lower spikelets
in each pair glabrous or with hairs that remain appressed at maturity;
lowest panicle nodes glabrous or with hairs less than 0.4 mm long ..... 29.
D. bicornis |
|
Spikelets 1.7-2.8 mm long; spikelets
homomorphic with respect to their pubescence; lowest panicle nodes with
hairs more than 0.4 mm long (35) |
|
Adaxial surfaces of
the blades evenly, sometimes densely, hairy; leaf sheaths usually with
scattered hairs; upper glumes 1/3-1/2 as long as the spikelets ..... 26.
D. horizontalis |
|
Adaxial surfaces of the blades glabrous
or with a few long hairs near the base; leaf sheaths glabrous or with
a few long hairs near the base; upper glumes 2/5-4/5 as long as the spikelets ..... 27.
D. nuda |
|
Lower glumes absent
or no more than 0.1 mm long (37) |
|
Lower glumes 0.1-0.8 mm long (38) |
|
Anthers
0.6-1.3 mm long; upper glumes 0.2-1.3 mm long, less than 0.4 times as
long as the spikelets ..... 31. D.
setigera |
|
Anthers 0.3-0.6 mm; upper glumes 1-2.2
mm long, 0.4-0.8 times as long as the spikelets ..... 27. D.
nuda |
|
Lower glumes 0.2-0.8
mm long; primary branches glabrous or with hairs shorter than 1 mm; spikelets
2.7-4.1 mm long ..... 30. D.
ciliaris |
|
Lower glumes 0.1-0.2 mm long; primary
branches often with scattered hairs 1-4 mm long; spikelets 1.7-2.8 mm
long (39) |
|
Adaxial surfaces of
the blades evenly hairy, sometimes densely so; leaf sheaths usually with
scattered hairs; upper glumes 0.3-0.5 times as long as the spikelets ..... 26.
D. horizontalis |
|
Adaxial surfaces of the blades glabrous
or with a few long hairs near the base; leaf sheaths glabrous or with
a few long hairs near the base; upper glumes 0.4-0.8 as long as the spikelets ..... 27.
D. nuda |
1. Digitaria arenicola (Swallen) Beetle
Sand Witchgrass
Plants perennial; loosely tufted, with long, creeping rhizomes. Culms
20-60 cm, erect; lower nodes glabrous or pubescent; upper nodes
glabrous. Leaves mainly cauline; sheaths usually glabrous, lower
sheaths sometimes pubescent; ligules 0.4-1 mm, truncate, entire to lacerate;
blades 5-11.5 cm long, 3-4.5 mm wide, glabrous, usually flat or folded.
Panicles simple, 12-24 cm long, 19-40 cm wide, open; nodes hispid;
branches divergent; lower primary branches 10-21 cm, with 1-several
sterile branches near the base; pedicels divergent, spikelets solitary.
Spikelets 3.5-4.6 mm long, 0.8-1 mm wide, elliptical. Lower glumes
0.2-0.5 mm; upper glumes 3-3.8 mm, 5-7-veined, densely villous between
the veins, hairs white, becoming purple at maturity; lower lemmas similar
to the upper glumes in size, texture, and pubescence; upper lemmas 3-3.7
mm, narrowly acute, dark brown; anthers 1.1-1.4 mm. Caryopses 1.5-2
mm. 2n = 36, 37.
Digitaria arenicola is endemic to deep sands along the coast of Texas,
a very restricted habitat and one that is being lost to the development of coastal
parks and housing.
2. Digitaria cognata (Schult.) Pilg
Fall Witchgrass
Plants perennial; cespitose, without rhizomes. Culms 30-56 cm, erect;
nodes glabrous. Leaves mainly cauline; sheaths glabrous or
sparsely to densely pubescent, sometimes with papillose-based hairs; ligules
0.2-1.5 mm, entire to lacerate; blades 2.4-12.6 cm long, 2-5.4 mm wide,
glabrous or pubescent. Panicles simple, 12.8-27.5 cm long, 16.5-44.5 cm
wide, open; branches divergent; lower primary branches 10.5-24 cm,
often with 1-several sterile branches near the base; pedicels divergent,
spikelets solitary. Spikelets 2.2-3.1 mm long, 0.7-1.1 mm wide, obovate
or broadly elliptic. Lower glumes 0.1-0.8 mm; upper glumes 1.8-2.8
mm, 3(5)-veined, glabrous or pubescent between the veins, hairs appearing as a
narrow stripe; lower lemmas similar to the upper glumes in length, texture,
and pubescence, 7-veined, veins unequally spaced, lateral veins closer together
than the 3 central veins; upper lemmas 1.9-2.9 mm, glabrous, dark brown,
narrowly acute; anthers 0.5-0.7 mm, yellow or purple. Caryopses
1.3-1.6 mm. 2n = 36.
Digitaria cognata grows in dry, sandy soils in the eastern portion of the
Flora region, from southern Ontario and Vermont through the United States
and thence to southern Mexico.
3. Digitaria pubiflora (Vasey) Wipff
Western Witchgrass
Plants perennial; cespitose, with or without rhizomes. Culms 20-70
cm, erect; nodes glabrous or pubescent . Leaves mainly cauline;
sheaths glabrous or sparsely to densely pubescent, sometimes with papillose-based
hairs; ligules 0.5-2.2 mm, entire to lacerate; blades 1.3-7.7 cm
long, 1.5-4.7 mm wide, glabrous or sparsely to densely pubescent. Panicles
simple, 4.5-20 cm long, 5.5-31 cm wide, open; branches divergent; lower
primary branches 3.6-17.7 cm, often with 1-several sterile branches near the
base; pedicels divergent, spikelets solitary. Spikelets 2.3-3.3
mm long, 0.6-1 mm wide, narrowly elliptic. Lower glumes 0.1-0.4 mm; upper
glumes 1.8-2.9 mm, 3-veined, densely pubescent between the veins, hairs white,
becoming purple at maturity; lower lemmas similar to the upper glumes in
length, texture, and pubescence, 5-veined, veins equidistant; upper lemmas
1.9-2.6 mm, glabrous, dark brown, narrowly acute; anthers 0.3-0.5 mm, yellow,
red, or purple. Caryopses 1.3-1.6 mm. 2n = 36 or (more commonly)
72.
Digitaria pubiflora grows in dry, sandy or rocky soils from Arizona to
central Texas and south to central Mexico.
4. Digitaria tomentosa (J. König ex Rottler) Henrard
Plants perennial; cespitose, not rhizomatous. Culms 40-90 cm, erect,
geniculate. Lower sheaths densely villous; upper sheaths with scattered
papillose-based hairs; ligules 1.5-3 mm; blades 4-7(12) cm long,
3-5 mm wide, villous to nearly glabrous, usually sparsely hairy near the ligules.
Panicles simple, 10-18 cm, open; branches divergent; pedicels
0.4-3 mm, divergent, spikelets solitary. Spikelets 2-2.5 mm, elliptical,
apiculate. Lower glumes absent or to 0.2 mm; upper glumes absent
or to 0.6 mm, veinless; lower lemmas as long as the spikelets, 5-veined,
margins and intercostal regions more or less pubescent; upper lemmas minutely
rugose, dark brown. 2n = 36.
A native of southern India and Ceylon, Digitaria tomentosa is a noxious
weed that is not known to occur in the Flora region. It is included here
to help ensure that any introduction is correctly identified.
5. Digitaria gracillima (Scribn.) Fernald
Plants perennial; in dense tufts, not rhizomatous. Culms 60-100
cm, erect. Sheaths villous, particularly the lower sheaths; ligules
0.2-0.4, fimbriate; blades to 47 cm long, 1-2.1 mm wide, involute, glabrous
and smooth abaxially, scabrous adaxially, sometimes with a few long hairs near
the base. Panicles of 2-3(5) spikelike primary branches on elongate rachises;
primary branches 8-13(20) cm, narrowly winged, wings no more than 1/2 as
wide as the midribs, with spikelets in unequally pedicellate groups of 3-4(5);
secondary branches rarely present; longest pedicels to 5 mm. Spikelets
1.7-2.3 mm, elliptical, glabrous. Lower glumes absent; upper glumes
0.9-1 mm, less than 1/2 as long as the spikelets, 3-veined, glabrous, broadly
rounded to truncate; lower lemmas slightly shorter than the spikelets,
5-veined, glabrous; upper lemmas smooth, brown when immature, dark brown
at maturity. 2n = unknown.
Digitaria gracillima is a rare species, endemic to scrub and dry pinelands
of peninsular Florida. It used to be interpreted as including D.
bakeri, but differs from that species both morphologically and ecologically.
6. Digitaria bakeri (Nash) Fernald
Plants perennial; cespitose. Culms 40-90 cm, erect, unbranched,
glabrous; nodes 1-2. Sheaths densely hairy, hairs papillose-based;
ligules 0.8-2.2 mm; blades 10-24 cm long, 2-4.5 mm wide, with papillose-based
hairs. Panicles with 2-3 spikelike primary branches on 4-7 mm rachises;
secondary branches rarely present; primary branches (5)10-22 cm,
axes 0.5-0.6 mm wide, not wing-margined, middle portions of the branches with
spikelets in groups of 3; pedicels appressed to the axes. Spikelets
2.3-2.4 mm, lanceolate to oblanceolate-elliptic; lower glumes absent; upper
glumes1.4-1.5 mm, more than 1/2 as long as the spikelets, 3-veined, truncate
to acute, mostly glabrous, apices sparsely hairy; lower lemmas about as
long as the spikelets, 7-veined, mostly glabrous, apices sparsely hairy; upper
lemmas 2.3-2.4 mm, dark brown to black, apiculate; anthers 1-1.1 mm.
2n = unknown.
Digitaria bakeri grows in pastures, particularly horse pastures, from Florida
through Mexico to Panama. It has been treated until recently as a synonym of D.
gracillima, but differs from that species both morphologically and ecologically.
It is probably more widespread in Florida than the map suggests but, because of
its inclusion in D. gracillima, little information is available at present.
7. Digitaria filiformis (L.) Koeler
Slender Crabgrass
Plants annual, or short-lived perennials; cespitose, not rhizomatous.
Culms (10)25-150 cm, erect or decumbent, branching, sometimes rooting
at the lower nodes; nodes 3-6. Sheaths keeled, basal sheaths usually
with papillose-based hairs, rarely glabrous; ligules 0.3-1.5 mm; blades
2-18 cm long, 1-6 mm wide, flat or involute, glabrous, scabrous, or pilose.
Panicles with 2-7 spikelike primary branches, these digitate or the rachises
to 1 cm; longest primary branches 3-25 cm long, 0.2-0.4 mm wide, axes
triquetrous, not wing-margined, with spikelets in groups of 2-5 on the lower
and middle portions. Spikelets 1.3-2.8 mm. Lower glumes absent
or to 0.1 mm; upper glumes 1-2 mm long, from 3/4 to almost as long as
the spikelets, almost glabrous or sparsely to densely pubescent with clavate
to capitate hairs (use 20× magnification), glume apices rounded; lower
lemmas equaling the spikelets, glabrous or glandular-pubescent, 5-7-veined,
veins unequally spaced, outer 3 veins on each side closer to each other than
the midvein is to the inner lateral veins; upper lemmas 1.3-2 mm, apiculate,
dark brown at maturity; anthers 0.3-0.6 mm. 2n = 36, 54.
Digitaria filiformis grows throughout the warmer parts of the eastern
United States. Digitaria filiformis var. filiformis, the most widespread
of its varieties, extending into Mexico.
1 |
Lower lemmas
glabrous ..... var. laeviglumis |
Lower lemmas pubescent (2) |
|
Basal leaf sheaths glabrous;
cauline blades about 1 mm wide, folded or involute ..... var. dolichophylla |
|
Basal leaf sheaths with papillose-based
hairs; cauline blades 1-6 mm wide, flat (3) |
|
Spikelets 1.3-1.9 mm
long; panicle branches 3-13 cm long; culms 10-80 cm tall ..... var. filiformis |
|
Spikelets 2-2.8 mm long; panicle branches
10-25 cm long; plants 75-150 cm tall ..... var. villosa |
Digitaria filiformis var. dolichophylla (Henrard)
Wipff
Culms 50-115 cm. Basal leaf sheaths glabrous;
cauline leaf blades about 1 mm wide, usually involute. Spikelets
1.5-1.6 mm; lower lemmas pubescent.
Digitaria filiformis var. dolichophylla is an uncommon species
of moist pine barrens and open ground in southern Florida.
Digitaria filiformis (L.) Koeler var. filiformis
Culms 10-80 cm. Basal leaf sheaths with papillose-based hairs; cauline
leaf blades 1-6 mm wide, flat. Panicle branches 3-13 cm. Spikelets
1.3-1.9 mm; lower lemmas pubescent.
Digitaria filiformis var. filiformis is a weed of sandy fields and
open, disturbed ground in the southeastern United States and Mexico.
Digitaria filiformis var. laeviglumis (Fernald)
Wipff
Culms 75-150 cm. Basal leaf sheaths with papillose-based
hairs or glabrous; blades 1-6 mm, flat. Spikelets 1.8-2.5 mm;
lower lemmas glabrous.
Digitaria filiformis var. laeviglumis is endemic to sandy soils
in New England.
Digitaria filiformis var. villosa (Walter) Fernald
Culms 75-150 cm. Basal leaf sheaths with papillose-based hairs;
cauline leaf blades 1-6 mm wide, flat. Panicle branches 10-25 cm.
Spikelets 2-2.8 mm; lower lemmas pubescent.
Digitaria filiformis var. villosa has essentially the same geographic
range as var. filiformis and grows in similar habitats. Further study may show that the two varieties
should be combined.
8. Digitaria leucocoma (Nash) Urb.
Plants perennial; cespitose. Culmsto 100 cm, erect, not branching
at the lower nodes; nodes 1-2. Sheaths with appressed hairs,
lower sheaths densely hairy, upper sheaths sparingly hairy near the base,
otherwise glabrous; ligules 2-3 mm; blades 10-40 cm long,
to 3 mm wide, usually flat, involute when dry. Panicles with 2-4
spikelike branches on 4-6 cm rachises; primary branches 20-25
cm, axes triquetrous, not winged, with spikelets in unequally pedicellate
groups of 3(-5) on the basal 1/2; secondary branches rarely present,
longer pedicels often adnate to the branch axes basally. Spikelets 2.2-2.5
mm long, 0.8 mm wide, elliptic, acute. Lower glumes absent; upper
glumes 3-veined, margins
and intercostal regions with long, glandular-tipped hairs; lower lemmas
7-veined, margins and the region between the 2 inner marginal veins with
long glandular hairs; upper lemmas light to dark brown at maturity,
striate, apiculate. 2n = unknown.
Digitaria leucocoma is known only from high pinelands near Lake Ella, Lake
County, Florida. It has been treated in the past as a synonym of D. filiformis
var. villosa.
9. Digitaria hitchcockii (Chase) Stuck.
Plants perennial; rhizomatous, rhizomes short, giving the
plants hard, knotty, much-branched bases. Culms 20-55 cm,
erect, sometimes geniculate, not rooting at the lower nodes. Basal sheaths tomentose; culm sheaths
glabrous or variously pubescent (puberulent, ciliate, or sparsely
hirsute); ligules (0.1)0.5-1(1.5) mm, ciliate; blades 2-5.5
cm long, 2-3 mm wide. Panicles with 3-6 spikelike primary branches
on 6-10(15) cm rachises; primary branches 1-6 cm, not or only
narrowly winged, with spikelets in unequally pedicellate pairs, pedicels
not adnate to the branch axes; shorter
pedicels 1.5-2 mm; longer pedicels 3-4 mm. Spikelets homomorphic,
2.5-3.1 mm (including pubescence), 2.4-3 mm (excluding pubescence). Lower glumes 0.3-1
mm, veinless; upper glumes 2.1-3 mm (including pubescence), as
long as or exceeding the upper florets by no more than 0.5 mm, 3-veined,
densely appressed-pubescent, hairs 0.5-1 mm, white to purple, tapering
or parallel-sided, not spreading at maturity; lower lemmas 2.3-3.1
mm (including pubescence), as long as or exceeding the upper lemmas by
up to 0.5 mm, 5-veined, veins equally spaced, intercostal regions densely
appressed-pubescent, hairs 0.5-1 mm, white to purple, tapering or parallel-sided,
not spreading at maturity; upper lemmas 2.2-2.5 mm,
brown when immature, dark brown at maturity. Caryopses 2.1-3.4
mm. 2n = 36.
Digitaria hitchcockii is an uncommon species of open, dry, gravelly
slopes in southwestern Texas and northern Mexico.
10. Digitaria patens (Swallen) Henrard
Plants perennial; cespitose, neither rhizomatous nor stoloniferous. Culms
40-90 cm, erect, sometimes geniculate, not rooting, at the lower nodes. Leaves
mainly cauline; basal sheaths villous; upper sheaths glabrous or
sparsely to densely hirsute, hairs papillose-based; ligules (1)1.5-4 mm,
entire to lacerate; blades 5-15 cm long, 1-4 mm wide, glabrous or sparsely
pubescent. Panicles with 4-10 spikelike primary branches on (4)10-18 cm
rachises; primary branches 4-10 cm, usually divergent at maturity, varying
to ascending, axes not wing-margined, with spikelets in unequally pedicellate
pairs; internodes (4.5)6-15 mm (mid branch); secondary branches
rarely present; shorter pedicels 2-2.5 mm; longer pedicels 7-8 mm;
terminal pedicels of primary branches 7.4-20 mm. Spikelets homomorphic,
3.7-5.8 mm (including pubescence), 2.9-4.3 mm (excluding pubescence). Lower
glumes 0.3-0.5 mm; upper glumes 2.4-3.5 mm (excluding pubescence),
3-veined, densely villous, hairs 1.5-4 mm, silvery-white to purple, spreading
at maturity; lower lemmas 2.8-4.2 mm (excluding pubescence), exceeding
the upper lemmas by 0.8-2.2 mm, 5-veined and the veins equally spaced or 7-veined
and the lateral veins closer to each other than to the central vein, margins densely
villous, hairs 1.5-4 mm, silvery-white to purple, spreading at maturity, apices
acuminate; upper lemmas 2.6-3.2 mm, lanceolate, brown when immature, dark
brown at maturity, acuminate. 2n = 72.
Digitaria patens is endemic to southwestern and southern Texas and adjacent
Mexico. It grows in well-drained, usually sandy soils, often in disturbed habitats.
Gould (1975) suggested that it might be an octoploid derivative of D.
californica.
11. Digitaria californica (Benth.) Henrard
Plants perennial; cespitose, neither rhizomatous nor stoloniferous. Culms
40-100 cm, erect, sometimes geniculate, not rooting, at the lower nodes. Basal
sheaths villous; upper sheaths glabrous, densely villous or densely
tomentose, or sparsely to densely hairy, with papillose-based hairs; ligules (1)1.5-6
mm, entire or lacerate, not ciliate; blades 2-12(18) cm long, 2-5(7)
mm wide, glabrous or the adaxial surfaces sparsely to densely villous or tomentose.
Panicles with 4-10 spikelike primary branches on 5-10 cm rachises, rarely
with secondary branches; primary branches 3-6 cm, appressed to ascending,
axes not wing-margined; internodes 2-5.5 mm (mid branch), with spikelets
in unequally pedicellate pairs;secondary branches rarely present; pedicels
not adnate to the branch axes; shorter pedicels 0.1-0.3 mm; longer
pedicels 1-2 mm; terminal pedicels of branches 1.7-6(7) mm. Spikelets
homomorphic, (3.7)4-7.5 mm (including pubescence), 3-5.4 mm (excluding pubescence).
Lower glumes 0.4-0.6 mm; upper glumes 2.5-5.1 mm (excluding pubescence),
narrower than the upper florets, 3-veined, densely villous, hairs 1.5-5 mm,
silvery-white to purple, widely divergent at maturity; lower lemmas 2.7-5
mm (excluding pubescence), pubescence exceeding the upper florets by 2.2-4 mm,
7-veined, veins unequally spaced, only the 3 or 5 central veins visible, margins
and outer lateral veins densely pubescent, hairs 1.5-5 mm, silvery-white to
purple, widely divergent at maturity, intercostal regions glabrous, apices attenuate
(acuminate); upper lemmas 2.5-3.4 mm, ovate-lanceolate, brown to dark
brown, acuminate. Caryopses 1.3-2 mm. 2n = 36, 54, 70, 72.
Digitaria californica grows on plains and open ground from Arizona, southern
Colorado, and Oklahoma through Mexico and Central America to South America.
The name reflects the fact that the first collection was made in Baja California,
Mexico. Plants in the Flora region belong to D. californica (Benth.)
Henrard var. californica. They differ from those of D. californica
var. villosissima Henrard in having densely villous, rather than densely
tomentose, leaves.
12. Digitaria insularis (L.) Mez ex Ekman
Plants perennial; cespitose, shortly rhizomatous, with knotty bases.
Culms 80-130 cm, erect, with densely villous cataphylls, branching from
the lower and middle nodes. Sheaths usually sparsely to densely papillose-hirsute,
occasionally glabrous; ligules 4-6 mm, usually lacerate, not ciliate;
blades 20-50 cm long, 10-17 mm wide, lax, smooth or scabridulous abaxially,
scabridulous to scabrous adaxially. Panicles 20-35 cm long, 2-10 cm wide,
with numerous spikelike primary branches; primary branches 10-15 cm,
appressed to ascending at maturity, axes not wing-margined or with wings less
than 1/2 as wide as the midribs; internodes 3-4.5(6) mm (mid branch),
with spikelets in unequally pedicellate pairs; secondary branches rarely
present; pedicels not adnate to the branches; shorter pedicels
0.7-2 mm; longer pedicels 2.5-5 mm; terminal pedicels 2-5 mm.
Spikelets 5.5-8.2 mm (including pubescence), 4.2-5.9 mm (excluding pubescence),
narrowly ovate, acuminate. Lower glumes 0.6-0.8 mm; upper glumes
3.5-4.5 mm, 3-5-veined, pubescent on the margins; lower lemmas 4.1-5.7
mm (exceeded 1.5-5 mm by pubescence), narrowly ovate, 7-veined, pubescent between
most, sometimes all, of the veins and on the margins, veins usually obscured
by a dense covering of golden-brown hairs, hairs 3-6 mm, spreading at maturity,
intercostal regions on either side of the midvein glabrous or pubescent with
shorter, fine, white hairs, sometimes intermixed with the golden-brown hairs;
upper lemmas 3.2-4.5 mm, narrowly ovate, brown when immature, dark brown
at maturity, acuminate; anthers 1-1.2 mm. 2n = 36.
Digitaria insularis grows in low, open ground of the southern United
States, and extends to the West Indies, Mexico, and through Central America
to Argentina.
13. Digitaria serotina (Walter) Michx.
Plants annual; often mat-forming. Culms 10-30 cm, decumbent and
rooting at the lower nodes. Sheaths conspicuously and densely hairy,
longer hairs 1.5-2.5 mm, papillose-based, shorter hairs about 0.5 mm, not papillose-based;
ligules 1.5-2.5 mm; blades 2-9 cm long, 3-8 mm wide, conspicuously
hairy on both surfaces, longer hairs 1.5-2.5 mm, papillose-based, shorter hairs
about 0.5 mm, not papillose-based. Panicles with 2-9 spikelike primary
branches, digitate or on rachises to 4 cm; primary branch axes 3-10 cm,
wing-margined, wings wider than the midribs, lower and middle portions with
spikelets in groups of 3; secondary branches rarely present; shortest
pedicels 0.5-0.8 mm; midlength pedicels 1.5-2 mm; longest pedicels
3-3.5 mm, adnate to the branch axes basally. Spikelets homomorphic, 1.5-1.8
mm, lanceolate. Lower glumes absent; upper glumes 1/6-1/3 as long
as the spikelets, margins and apices with appressed white hairs, hairs about
0.3 mm; lower lemmas 7-veined, veins equally spaced, appressed-pubescent
between the inner lateral veins and on the margins, hairs 0.3-0.5 mm, minutely
verrucose (use 50× magnification); upper lemmas yellow or tan at
maturity. 2n = unknown.
Digitaria serotina is native to the coastal plain of the southeastern
United States. It has also been found in Cuba, possibly as an introduction,
and on a ballast dump in Philadelphia, Pennsylvania. Its densely hairy sheath
and short, densely hairy blades make this one of the more distinctive species
of Digitaria in the Flora region.
14. Digitaria longiflora (Retz.) Pers.
Plants of indefinite duration; stoloniferous, stolons long and branching.
Culms 10-60 cm, occasionally branching from the lower nodes. Leaves
3-4, clustered near the base; sheaths usually glabrous; ligules
0.5-1 mm; blades 1.5-4 cm long, 3-5 mm wide, mostly glabrous, bases subcordate
and ciliate, with 0.6-1 mm papillose-based hairs. Panicles with 2(-4)
spikelike primary branches, digitate; primary branches 2-5 cm, strongly
divergent; branch axesabout 1 mm wide, wing-margined, wings wider than
the central midribs, with spikelets in unequally pedicellate groups of 3; secondary
branches rarely present; shortest pedicels about 0.3 mm; middle
pedicels about 1 mm; longest pedicels 1.5-2 mm, adnate to the branch
axes basally; axillary panicles not present. Spikelets 1.2-1.5
mm, elliptic or slightly obovate, acute. Lower glumes absent; upper
glumes equaling or almost equaling the spikelets, 5-veined, minutely pubescent
between the veins and on the margins; lower lemmas subequal to the upper
glumes, 7-veined, usually pubescent on the margins and lateral veins, occasionally
glabrous, hairs, if present, 0.2-0.4 mm; upper lemmas about 1.2 mm, pale
brown or pale gray, becoming light brown at maturity, acute; anthers
0.8-0.8 mm. 2n = 18.
Digitaria longiflora is native to Africa and Asia. It is now established
in disturbed areas of Florida, growing on railroad grades and in pastures and
lawns.
The illustration of Digitaria longiflora was
inadvertently based on a misidentified specimen of D. fulvescens (J.
Presl) Henrard. The two species differ in little more than the pubescence
of their lemmas, D. longiflora having pubescent lemmas and D.
fulvescens glabrous lemmas (G. Davidse, pers. comm.). They should,
perhaps, be considered a single species (J. Wipff, pers. comm.). If
they are treated as a single species, the correct name for the species
is D. longiflora. [Note added by M.E. Barkworth, June 18, 2005.]
15. Digitaria floridana Hitchc.
Plants annual or of indefinite duration; not stoloniferous. Culms
20-30 cm, decumbent and rooting at the nodes; nodes glabrous. Sheaths
mostly glabrous, throats with papillose-based hairs; blades 4-7 cm long,
3-6 mm wide, glabrous. Panicles with 2-4 spikelike primary branches,
if more than 2, rachises 7-20 mm and the branches racemose; primary branches
3-6 cm, terminal branch erect, the other(s) usually divergent, axes wing-margined,
wings wider than the midribs, with spikelets in unequally pedicellate groups
of 3 on the basal and mid-portions; secondary branches rarely present;
shortest pedicels about 0.05 mm; middle pedicels about 0.1 mm;
longest pedicels 0.2-0.3 mm, adnate to the branch axes basally; axillary
panicles not present. Spikelets homomorphic, 1.5-1.7 mm, lanceolate.
Lower glumes absent; upper glumes almost equaling the upper lemmas,
conspicuously 3-veined; lower lemmas slightly longer than the upper lemmas,
7-veined, veins unequally spaced, all the intercostal regions sparsely hairy,
hairs about 0.3 mm; upper lemma slight brown when immature, dark brown
at maturity. 2n = unknown.
Digitaria floridana is a rare species that is known only from sandy pine
woods in Hernando County, Florida.
16. Digitaria ischaemum (Schreb.)
Muhl.
Smooth Crabgrass, Digitaire Astringente
Plants annual or of indefinite duration. Culms
20-55(70) cm, decumbent, branching and rooting at the lower nodes; nodes
3-4. Sheaths glabrous or sparsely pubescent; ligules 0.6-2.5 mm;
blades 1.5-9 cm long, 3-5 mm wide, glabrous, with a few papillose-based
hairs basally. Panicles terminal and axillary; terminal panicles
with 2-7 spikelike primary branches, subdigitate or on 0.5-2 cm rachises; primary
branches 6-15.5 cm, axes wing-margined, wings at least 1/2 as wide as the
midribs, with spikelets in groups of 3, lower portions of the longer pedicels
adnate to the axes; secondary branches rarely present; axillary inflorescences
always present in some of the lower sheaths, entirely or partially concealed.
Spikelets 1.7-2.3 mm, homomorphic, narrowly elliptic. Lower glumes
absent or a veinless, membranous rim; upper glumes 1.3-2.3 mm, from 3/4
as long as to equaling the upper lemmas, appressed-pubescent; lower lemmas
1.7-2.3 mm, 7-veined, veins unequally spaced, smooth, pubescent; upper lemmas
dark brown at maturity; anthers 0.4-0.6 mm. 2n = 36.
Digitaria ischaemum is a Eurasian weed that is now common in lawns, gardens,
fields, and waste ground in warm-temperate regions throughout the world, including
much of the Flora region. Larger plants with 5-7 inflorescence branches
8-15 cm long have been called D. ischaemum var. mississippiensis (Gatt.) Fernald, but
they intergrade with more typical plants, and so do not merit taxonomic recognition.
17. Digitaria violascens Link
Plants annual or of indefinite duration. Culms 15-60 cm, erect,
usually not branching from the upper nodes; nodes 3-4. Sheaths
glabrous or sparsely pubescent; ligules 0.6-2.5 mm; blades 1.5-9
cm long, 3-5 mm wide, glabrous, with papillose-based hairs basally. Panicles
with 2-7 spikelike primary branches in 1-2 verticils; primary branches
3-12 cm, erect to ascending, axes 0.6-1 mm wide, wing-margined, wings at least
1/2 as wide as the midribs, lower and middle portions of the branches with spikelets
in groups of 3(4, 5); secondary branches rarely present; axillary
inflorescences absent. Spikelets 1.2-1.7 mm, homomorphic, narrowly
elliptic. Lower glumes absent or a veinless, membranous rim; upper
glumes 1.2-1.4 mm, 1/2 as long as to almost equaling the upper lemmas, 3-veined,
appressed-pubescent, hairs minutely verrucose; lower lemmas 1.2-1.7 mm,
5-7-veined, veins equally spaced, region between the 2 inner lateral veins and
the margins appressed-pubescent, hairs 0.3-0.5 mm, smooth or minutely verrucose
(use 50× magnification), verrucose hairs most abundant near the lemma
bases; upper lemmas light brown when immature, dark brown at maturity;
anthers 0.4-0.6 mm. 2n = 36.
Digitaria violascens is a weedy species that is native to tropical regions
of the Eastern Hemisphere. It is now established in the Flora region,
primarily in the southeastern United States, and in Mexico and Central America.
It grows in disturbed sites.
18. Digitaria abyssinica (Hochst. ex A. Rich.) Stapf
Plants perennial; rhizomatous, mat-forming. Culms 5-80 cm, decumbent,
occasionally rooting at the lower nodes, branching freely at the base, erect
portion 20-40 cm; nodes 2-6. Sheaths of midculm leaves glabrous
or hirsute, with papillose-based hairs; ligules 0.8-2.1 mm; blades
4-15 cm long, 3-10 mm wide, glabrous or sparsely pubescent with papillose-based
hairs. Panicles with 2-25 spikelike primary branches on 1-9 cm rachises;
primary branches 2-11 cm, axes not winged or narrowly winged, wings less
than 1/2 as wide as the midribs, with spikelets in unequally pedicellate pairs;
secondary branches rarely present; pedicels not adnate to the
branch axes. Spikelets 1.5-2.5 mm long, 0.8-0.95 mm wide, ovate-elliptic
to broadly elliptic, usually plump, usually purple-tinged. Lower glumes
absent or to 0.8 mm and acute; upper glumes 1.2-2.4 mm, from 0.8 times
as long as to almost equaling the spikelets, glabrous, 3-7-veined, veins usually
prominent; lower lemmas 1.5-2.5 mm, usually glabrous, occasionally obscurely
puberulent on the margins or, very rarely, distinctly pubescent, 7-veined, veins
usually prominent; upper lemmas light brown, gray, and purple. 2n
= 36.
Introduced from Africa, Digitaria abyssinica is not known to be established
in the Flora region, although it has occasionally been cultivated in
the southern United States. It is considered a potentially serious weed threat
by the U.S. Department of Agriculture.
19. Digitaria pauciflora Hitchc.
Plants perennial; not rhizomatous. Culms 50-100 cm, erect to somewhat
decumbent, not rooting at the lower nodes, usually branching at the aerial nodes.
Sheaths grayish-villous; ligules 1.5-2 mm; blades to 12
cm long, 2-2.2 mm wide, flat or folded, densely grayish-villous on both surfaces.
Panicles with 2-3 spikelike primary branches, secondary branches not
present; primary branches 5-11 cm, axes not winged, without spikelets
or with widely spaced abortive spikelets on the proximal 1-1.5 cm, with spikelets
in unequally pedicellate pairs at midlength; shorter pedicels about 2
mm; longer pedicels about 3 mm, not adnate to the branch axes. Spikelets
2.7-3.2 mm, appressed, glabrous. Lower glumes minute, rounded, erose;
upper glumes slightly shorter than the spikelets, 3-veined, glabrous;
lower lemmas7-veined, glabrous; upper lemmas gray or yellow when
immature, becoming purple at maturity. 2n = unknown.
Digitaria pauciflora is known only from the type collection, which was
collected in pinelands of Dade County, Florida.
20. Digitaria simpsonii (Vasey) Fernald
Plants of indefinite duration; not rhizomatous. Culms 80-120 cm,
erect or decumbent and rooting at the lower nodes, not branching at the aerial
nodes. Sheaths hirsute, with papillose-based hairs, those of the innovation
sheaths compressed-keeled; ligules 1-2 mm; blades 7-30 cm long,
3-5 mm wide, flat, pilose above and below. Panicles with 6-8 spikelike
primary branches on 4-6 cm rachises; primary branches 8-13 cm, axes triquetrous,
narrowly winged, wings less than 1/2 as wide as the midribs, lower and middle
portions of the branches with spikelets in appressed, unequally pedicellate
pairs; secondary branches rarely present; axillary inflorescences
not present; pedicels not adnate to the branch axes. Spikelets
about 3 mm, elliptic lanceolate, acute. Lower glumes absent or minute
and hyaline; upper glumes 7-9-veined, glabrous or obscurely pubescent;
lower lemmas 7-9-veined, glabrous or obscurely pubescent; upper lemmas
elliptic, yellow or gray, becoming purple at maturity, slightly apiculate. 2n
= unknown.
Digitaria simpsonii is a rare species, known only from sandy fields in
Florida.
21. Digitaria texana Hitchc.
Plants perennial; not rhizomatous. Culms 30-80 cm, sometimes erect,
usually decumbent and branching and rooting at the lower nodes, not branching
at the upper nodes. Sheaths of the lower leaves villous, those of the
upper leaves sometimes glabrous, those ofthe flag leaves without axillary panicles;
ligules 1.5-2 mm; blades 10-15 cm long, 2-7 mm wide, hirsute to
nearly glabrous. Panicles with 5-10 spikelike primary branches on 1-4
cm rachises; primary branches 5-10(13) cm, axes triquetrous, narrowly
winged, wings less than 1/2 as wide as the midribs, lower and middle portions
of the branches with paired spikelets; secondary branches rarely present.
Spikelets 2-3.6 mm, narrowly ovate-oblong, acute. Lower glumes
absent; upper glumes almost as long as the spikelets, 3(5)-veined, shortly
villous on the margins and sometimes between the margins; lower lemmas
similar to the upper glumes; upper lemmas gray or yellow, sometimes purple-tinged,
becoming purple at maturity. Caryopses narrowly oblong. 2n = 54.
Digitaria texana grows in sandy oak woods and prairies of southern Texas
and Florida.
22. Digitaria didactyla Willd.
Blue Couch
Plants perennial; stoloniferous and rhizomatous, mat-forming. Culms
15-40(63) cm, rooting and branching from the lower nodes. Sheaths densely
to sparsely hairy, with 3-5 mm papillose-based hairs; ligules 1-1.5 mm;
blades 2.5-7 cm long, 1-3 mm wide, flat or folded, usually glabrous, green
to bluish-green. Panicles with 2-4 spikelike primary branches digitately
arranged; primary branches 2-7 cm, axes wing-margined, wings at least 1/2
as wide as the midribs, spikelets somewhat imbricate, in unequally pedicellate
pairs; secondary branches rarely present; pedicels not adnate to
the branches; shorter pedicels 1-1.5 mm; longer pedicels 2-3 mm;
axillary panicles not present. Spikelets homomorphic, 2-2.8 mm long,
about 0.8 mm wide. Lower glumes to 0.3 mm, triangular; upper glumes
from 1/2-3/4 as long as the spikelets, 3-veined, pilose on the margins and sometimes
between the veins; upper lemmas equaling the spikelets, prominently 7-veined,
veins equally spaced, margins and sometimes the intercostal regions pilose, hairs
0.3-0.5 mm; upper lemmas slightly shorter than the lower lemmas, almost
smooth, gray, sometimes purple-tinged, at maturity. 2n = unknown.
A native of Africa, Digitaria didactyla is often cultivated as a lawn grass
in tropical and subtropical regions. It has been grown experimentally in Florida,
but is not otherwise known from the Flora region.
23. Digitaria eriantha Steud.
Plants perennial; sometimes stoloniferous, stolons to 6 m, or cespitose,
with or without rhizomes, rhizomes, if present, short, giving the plants knotty
bases. Culms 35-140 cm, erect or decumbent, not rooting at the basal
nodes. Basal sheaths glabrous or pubescent, often densely so, with 4-6
mm papillose-based hairs; ligules (1.8)3-5 mm, erose and ciliate; blades
5-40 cm long, 3-6 mm wide, scabridulous, often also papillose-hairy. Panicles
with 3-15 spikelike primary branches, digitate or with rachises to 3 cm;
primary branches 5-25 cm, wing-margined, wings wider than the midribs,
with spikelets in unequally pedicellate pairs; shorter pedicels 0.5-1.5
mm; longer pedicels 1.5-3 mm. Spikelets homomorphic, 2.8-3.5 mm,
narrowly lanceolate to narrowly elliptic. Lower glumes 0.3-0.5 mm, veinless,
acute; upper glumes 1.7-1.9 mm, wooly pubescent; lower lemmas
2.5-3.5 mm, 7-veined, veins unequally spaced and smooth, occasionally the lateral
veins scabridulous over the distal 1/4, margins and region between the 2 inner
lateral veins appressed-pubescent, with 0.5-1.5 mm hairs; upper lemmas
gray when immature, becoming brownish at maturity; anthers 1.2-1.6 mm,
purple. 2n = 36.
Digitaria eriantha is an African species that is widely cultivated in
warm climates as a pasture grass. Several cultivars have been released for forage
and hay use. The appearance of the spikelets varies considerably with the length
of the hairs, those of subsp. eriantha usually being longer than those of subsp. pentzii
The cultivar Digitaria umfolozi D.W. Hall ('Survenola'), a hybrid between D.
setivalva [= D. eriantha subsp. eriantha] and D.
decumbens [= D. eriantha subsp. pentzii] has been released
for use in the tropics and on well-fertilized upland soils in Florida. It is
described as having much wider leaf blades than any other cultivars that have
been released so far (usually 10-13 mm wide, rather than usually less than 8
mm) and glabrous leaf sheaths.
1 |
Plants cespitose ..... subsp.
eriantha |
Plants stoloniferous ..... subsp.
pentzii |
Digitaria eriantha Steud. subsp. eriantha
Plants cespitose, rhizomatous, rhizomes short. Basal sheaths hirsute.
Digitaria eriantha subsp. eriantha is seed-producing, but it is
not clear whether it is being grown in the Flora region.
Digitaria eriantha subsp. pentzii (Stent) Kok
Plants stoloniferous (the stolons to 6 m), sterile. Basal sheaths
glabrous or hirsute. 2n = 27 (for Digitaria decumbens).
In the Western Hemisphere, D. eriantha subsp. pentzii has traditionally
been referred to as D. decumbens Stent. It is widely cultivated as a forage grass throughout the tropics at low and
intermediate altitudes (up to 2000 m). It does not set seed; propagation is
by sprigging the stolons.
24. Digitaria milanjiana (Rendle) Stapf
Plants perennial; rhizomatous and stoloniferous. Culms 50-250
cm, erect or decumbent, rooting or not at the lower nodes. Basal sheaths
glabrous or variously pubescent (pilose, rarely tomentose or with papillose-based
hairs); upper sheaths glabrous; ligules 0.8-2.5 mm; blades
6-15(30) cm long, 3.5-8.5(13) mm wide, glabrous adaxially, rarely hirsute, with
papillose-based hairs basally, margins scabridulous. Panicles with 2-18
spikelike primary branches, these digitate or with rachises to 6 cm; primary
branches 5-25 cm, axes wing-margined, wings about as wide as the midribs,
with spikelets in unequally pedicellate pairs; secondary branches rarely
present; shorter pedicels 0.2-0.3 mm; longer pedicels 1-1.5 mm.
Spikelets homomorphic, 2.5-3.5 mm long, 0.7-0.9 mm wide, lanceolate.
Lower glumes 0.2-0.5 mm, acute to truncate; upper glumes (1.2)1.6-2.3
mm, from 1/5 as long as to almost equaling the spikelets; lower lemmas
2.5-3.5 mm, 7-veined, veins unequally spaced, midvein and lateral veins scabrous
at least on the distal 1/2, margins and region between the inner 2 lateral veins
with straight, yellowish, 0.6-1 mm hairs; upper lemmas gray to tan at
maturity. 2n = 18, 34, 36, 45, 54, 72(?).
Digitaria milanjiana is native to tropical and subtropical Africa. It
has been found as an escape from experimental plantings in Florida.
25. Digitaria velutina (Forssk.) P. Beauv.
Plants of indefinite duration; loosely cespitose to straggling. Culms
15-80 m, decumbent, rooting and branching at the lower nodes. Sheaths
pilose, with papillose-based hairs; ligules 1.8-2 mm; blades 4-15
cm long, 3-10 mm wide, pilose, with papillose-based hairs. Panicles with
5-18 spikelike primary branches on 2.5-5 cm rachises, lower branches usually
verticillate; primary branches 3.5-10 cm long, 0.3-0.5 mm wide, narrowly
wing-margined, wings less than 1/2 as wide as the midribs, with spikelets in
unequally pedicellate pairs; secondary branches often present, often
highly divergent; shorter pedicels 0.2-0.5 mm; longer pedicels
0.8-1.1 mm. Spikelets 1.5-2 mm long, about 0.5 mm wide, elliptic-lanceolate.
Lower glumes absent or to 0.2 mm; upper glumes 1.5-1.7 mm, usually
to 3/4 as long as the spikelets, 3-veined, villous between the veins, hairs
tapering or parallel-sided; lower lemmas about as long as the spikelets,
7-veined, veins unequally spaced, 2 veins crowded together near each margin,
3 inner veins well-separated, pubescent on the margins and between the inner
lateral veins, hairs about 0.2 mm, sometimes sparse, lateral veins smooth throughout
or scabridulous only on the distal 1/3; upper lemmas 1.5-1.7 mm, usually
gray at maturity, sometimes brown; anthers about 0.5 mm. 2n =
18.
Digitaria velutina is an African species, appearing on the noxious weed
list of the U.S. Department of Agriculture. It has been erroneously reported
as occurring in Texas (Kartesz and Meacham 1999).
26. Digitaria horizontalis Willd.
Plants of indefinite duration; sprawling. Culms to 1 m, erect
portion 20-25 cm, decumbent, rooting and branching freely at the nodes. Sheaths
usually with scattered papillose-based hairs, hairs more abundant on the lower
sheaths; ligules 1.5-1.8 mm, erose; blades 3-14 cm long, 3-9 mm
wide, evenly, often densely pubescent adaxially, hairs papillose-based. Panicles
with 2-14 spikelike branches attached to 4-15 cm rachises, lower branches whorled,
upper branches often paired or solitary; lower nodes with hairs more
than 0.4 mm; primary branches 4-12 cm, axes 0.4-0.7 mm wide, wing-margined,
wings at least 1/2 as wide as the midribs, often with scattered 1-4 mm hairs
proximally, with spikelets in unequally pedicellate pairs on the proximal and
middle portion of the branches; secondary branches rarely present; shorter
pedicels 0.3-0.5 mm; longer pedicels 1.3-2 mm. Spikelets homomorphic,
2.1-2.4 mm, narrowly ovate. Lower glumes 0.1-0.2 mm; upper glumes
1-1.1 mm, 1/3-1/2 as long as the spikelets, 3-veined, margins and apices ciliate;
lower lemmas about as long as the spikelets, lanceolate, 7-veined, lateral
3 veins on each side unequally or equally spaced, smooth or scabrous over the
distal 1/3, lemma margins and the region between the second and third veins
densely pubescent, hairs 0.05-0.1 mm, white; upper lemmas slightly shorter
than the lower lemmas, yellowish or grayish when immature, becoming light brown
at maturity, minutely striate. Caryopses about 1.8 mm, tan. 2n
= 36.
Digitaria horizontalis is native to tropical regions of the Americas.
It has been found in hammocks and disturbed areas in central and southern Florida
and at a few other locations in the southeastern United States, including ballast
dumps in Mobile, Alabama.
27. Digitaria nuda Schumach.
Plants annual or of indefinite duration. Culms 20-60 cm, glabrous,
decumbent, rooting and branching from the lower nodes, geniculate above. Sheaths
glabrous or with long hairs near the base; ligules 0.8-2.5 mm; blades
2-13.5 cm long, 1.5-2.5 mm wide, glabrous on both surfaces or the adaxial surface
with a few long hairs near the base. Panicles with 3-8 spikelike primary
branches, these digitate or with rachises to 2 cm long; lower panicle nodes
with hairs at least 0.4 mm; primary branches 4-15.5(20) cm long,
0.4-0.8 mm wide, axes wing-margined, wings more than 1/2 as wide as the midribs,
proximal portions of the branches often with scattered 1-4 mm hairs, with spikelets
in unequally pedicellate pairs on the lower and middle portions of the branches;
secondary branches absent; pedicels not adnate to the branches.
Spikelets homomorphic, 1.7-2.8 mm long, 0.5-0.8 mm wide. Lower glumes
absent or to 0.2 mm; upper glumes 1-2.2 mm, 0.4-0.8 times as long as
the spikelets; lower lemmas about as long as the spikelets, 7-veined,
veins smooth, lateral veins usually equally spaced, sometimes the inner lateral
veins more distant from the other 2, intercostal regions adjacent to the midveins
glabrous, those between the lateral veins with 0.5-1 mm hairs, hairs initially
appressed, sometimes strongly divergent at maturity; upper lemmas yellow
to gray when immature, becoming brown at maturity; anthers 0.3-0.6 mm.
2n = unknown.
Digitaria nuda is an African species thatis now established in tropical
regions throughout the world, including the Americas. So far as is known, it
has only been collected once in the Flora region.
28. Digitaria sanguinalis (L.) Scop.
Hairy Crabgrass, Digitaire Sanguine
Plants annual. Culms 20-70(112), often decumbent
and rooting at the lower nodes. Sheaths keeled, usually sparsely pubescent
with papillose-based hairs; ligules 0.5-2.6 mm; blades 2-11(14)
cm long, 3-8(12) mm wide, usually with papillose-based hairs on both surfaces,
sometimes glabrous. Panicles with 4-13 spikelike primary branches, these
subdigitate or on rachises to 6 cm; primary branches 3-30 cm long, 0.7-1.5
mmwide, flattened and winged, wings more than 1/2 as wide as the midribs, lower
and middle portion of the branches with spikelets in unequally pedicellate pairs,
pedicels not adnate to the branches; secondary branches rarely present.
Spikelets homomorphic, 1.7-3.4 mm long, 0.7-1.1 mm wide. Lower glumes
0.2-0.4 mm long, veinless; upper glumes 0.9-2 mm, 1/3-1/2 as long as
the spikelets, 3-veined, pubescent on the margins; lower lemmas usually
exceeded or equaled by the upper florets, sometimes exceeding them but by no
more than 0.2 mm, glabrous, 7-veined, lateral (or all) veins scabrous throughout
or smooth on the lower 1/3(1/2) and scabrous distally, 3 middle veins usually
widely spaced, remaining veins on each side close together and near the margins;
upper lemmas 1.7-3 mm, yellow or gray, frequently purple-tinged when
immature, often becoming brown at maturity; anthers 0.5-0.9 mm. 2n
= 36, 28, 34, 54.
Digitaria sanguinalis is a weedy Eurasian species that is now found in
waste ground of fields, gardens, and lawns throughout much of the world, including
the Flora region.
29. Digitaria bicornis (Lam.) Roem. & Schult.
Plants of indefinite duration; sometimes stoloniferous. Culms with
erect portion 10-85 cm, long-decumbent, rooting and branching at the lower nodes.
Sheaths with papillose-based hairs or the upper sheaths glabrous; ligules
1-4 mm; blades 3-14 cm long, 2-9 mm wide, mostly glabrous but the adaxial
surfaces with papillose-based hairs basally. Panicles with (2)3-6 spikelike
primary branches, these digitate or a few solitary branches below; lowest
nodes glabrous or with hairs less than 0.4 mm; primary branches 6.5-21
cm long, 0.6-1.3 mm wide, axes winged, wings at least 1/2 as wide as the midribs,
lower and middle portions with spikelets in unequally pedicellate pairs, pedicels
not adnate to the branches; secondary branches absent; shorter pedicels
about 0.2 mm; longer pedicels to 2 mm. Spikelets 2.6-3.7 mm, spikelet
pairs dimorphic in their pubescence and venation pattern of the lower lemmas.
Lower glumes absent or to 0.9 mm, deltoid or bifid; upper glumes
1.7-2.8 mm, 1/2-3/4 as long as the spikelets, 3-veined; lower lemmas
7-veined, veins smooth; lower lemmas of shortly pedicellate spikelets
with 3 equally spaced, glabrous or shortly pubescent central veins, lemma margins
and the region between the 2 lateral veins with appressed or spreading, 0.5-1
mm hairs; lower lemmas of long-pedicellate spikelets with unequally spaced
veins, midvein well-separatedfrom the 3 lateral veins, lateral veins crowded
together near the margins, lemma margins and the region between the 2 inner
lateral veins hairy with appressed or strongly divergent, 1-2 mm hairs, sometimes
also with longer, glassy yellow hairs; upper lemmas of all spikelets
usually yellow or gray, sometimes light brown, at maturity; anthers 0.5-0.6
mm. 2n = 54, 72.
Digitaria bicornis is a common species on the sandy coastal plain of
the southeastern United States. Its range extends through Mexico to Costa Rica
and northern South America, as well as to the West Indies. The Californian record
reflects a 1926 collection; the species is not known to be established in the
state.
30. Digitaria ciliaris (Retz.) Koeler
Southern Crabgrass
Plants annual or of indefinite duration. Culms 10-100 cm long,
erect portion 30-60 cm, long-decumbent, rooting and branching at the decumbent
nodes, sparingly branched or unbranched from the upper nodes; nodes 2-5,
glabrous. Sheaths with papillose-based hairs; ligules 2-3.5 mm,
erose; blades 1.5-14.4(18.9) cm long, 3-9 mm wide, flat, glabrous, a
few scattered papillose-based hairs at the base of the adaxial surfaces (occasionally
overthe whole adaxial surface), usually also scabrous on both surfaces. Panicles
with 2-10 spikelike primary branches, these digitate or in 1-3 whorls on rachises
to 2 cm; lowest panicle nodes with hairs more than 0.4 mm; primary
branches 3-24 cm long, 0.6-1.2(2) mm wide, glabrous or with less than 1
mm hairs, axes wing-margined, wings at least 1/2 as wide as the midribs, lower
and middle portions of the branches with spikelets in unequally pedicellate
pairs; secondary branches absent; shorter pedicels 0.5-1 mm; longer
pedicels 1.5-4 mm. Spikelets (2.7)2.8-4.1 mm long, homomorphic. Lower
glumes 0.2-0.8 mm, acute; upper glumes (1.2)1.5-2.7 mm, about 2/3
to almost as long as the spikelet, 3-veined, margins and apices pilose; lower
lemmas 2.7-4.1 mm, 7-veined, veins unequally spaced, outer 3 veins crowded
together near each margin, well-separated from the midvein, usually smooth,
occasionally the lateral veins scabridulous on the distal 1/3, margins and regions
between the 2 inner lateral veins hairy, hairs 0.5-1 mm (rarely glabrous), sometimes
also with glassy yellow hairs between the 2 inner lateral veins, these more
common on the upper spikelets; upper lemmas 2.5-4 mm, glabrous, yellow,
tan, or gray when immature, becoming brown, often purple-tinged (occasionally
completely purple) at maturity; anthers 0.6-1 mm. 2n = 36 [J.H. Hunziker, F.O. Zuloaga, O. Morrone, and A. Escobar. 1998. Estudios cromosómicos en Paniceae sudamericanas (Poaceae: Panicoideae). Darwiniana 35:29-36], 54.
Digitaria ciliaris is a weedy species, found in open, disturbed areas
in most warm-temperate to tropical regions, primarily in the eastern United
States. It is particularly abundant in the southeast. So far as is known, the
two varieties distinguished in the following key do not differ in any other
characters. They are recognized here pending further study.
1 |
Lower lemmas without glassy yellow
hairs ..... var. ciliaris |
Lower lemmas with glassy yellow hairs ..... var.
chrysoblephara |
Digitaria ciliaris var. ciliaris is the more common of the two varieties in the Flora region. Digitaria ciliaris var. chrysoblephara (Fig. & De Not.) R.R. Stewart is more common in southeast Asia, but it has been found in the northeastern United States.
31. Digitaria setigera Roth
Plants of indefinite duration. Culms to 120 cm tall, bases long-decumbent
and rooting at the lower nodes. Sheaths with papillose-based hairs; ligules
2.5-3.5 mm; blades 4-28 cm long, 4-12 mm wide, scabrous, usually with
some scattered papillose-based hairs on the base of the adaxial surfaces, sometimes
with hairs all over. Panicles with 3-11 spikelike primary branches in
1-several whorls, rachises to 6 cm; primary branches 5-15 cm, axes wing-margined,
wings more than 1/2 as wide as the midribs, lower and middle portions with spikelets
in unequally pedicellate pairs; secondary branches absent; shorter
pedicels 0.3-0.8 mm; longer pedicels 1.7-2.7 mm. Spikelets
2.4-3.5 mm, homomorphic, ovate. Lower glumes absent or to 0.1 mm; upper
glumes 0.2-1.3 mm, 1/6-1/3 as long as the spikelets, 1-3-veined, margins
and apices with appressed, white hairs about 0.5 mm, truncate or bilobed; lower
lemmas (5)7-veined, veins smooth or scabrous only over the distal 1/3, unequally
spaced, margins and lateral intercostal regions silky-ciliate; upper lemmas
tan or gray when immature, brown at maturity, acuminate; anthers 0.6-1.3
mm. 2n = 70, 72.
Digitaria setigera is native to southeastern Asia. It is now established
in tropical America, growing in disturbed habitats in Florida and Central America,
and probably in tropical South America. It has often been confused with D.
sanguinalis.
Plants in the Flora region belong to Digitaria setigera Roth var. setigera.
Unlike plants of D. setigera var. calliblepharata (Henrard) Veldkamp,
they do not have large, glassy hairs on their lower lemmas.