| Robert D. Webster |
Plants perennial; cespitose, often with
a knotty crown, sometimes rhizomatous, rhizomes usually short but elongate in
some species, rarely stoloniferous. Culms 0.8-6 m, erect. Leaves
cauline, not aromatic; sheaths usually glabrous, sometimes ciliate at the
throats; ligules membranous, ciliate; blades flat, lax, smooth,
usually glabrous. Inflorescences terminal, large, often plumose, fully
exserted panicles with evident rachises and numerous, ascending to appressed branches
terminating in multiple rames, branches alternate, sometimes naked below; rames with
numerous sessile-pedicellate spikelet pairs and a terminal triad of 1 sessile
and 2 pedicellate spikelets, internodes slender, without a translucent median
groove; disarticulation beneath the pedicellate spikelets and in the rames
beneath the sessile spikelets, sessile spikelets falling with the adjacent internode
and pedicel. Spikelet pairs homogamous and homomorphic, or almost so, not
embedded in the rame axes, dorsally compressed. Sessile spikelets: calluses
truncate, usually with silky hairs; glumes subequal, chartaceous to coriaceous,
glabrous or villous, 2-keeled, veins not raised; lower florets sterile;
lower lemmas hyaline or membranous; lower paleas absent or vestigial,
entire; upper florets bisexual; upper lemmas entire or bidentate,
muticous or awned; lodicules 2, truncate; anthers 2 or 3. Pedicels
neither appressed nor fused to the rame axes. Pedicellate spikelets well
developed, from slightly shorter than to equaling the sessile spikelets. x
= 10. Name from the Latin saccharum, sugar, a reference to the sweet juice.
Saccharum is a genus of 35-40 species that grow throughout the tropics
and subtropics. Nine species can be found in the Flora region; five are
native, two are grown as ornamentals, one is grown for agriculture, and one for
research. Some species of Saccharum hybridize
naturally with other, presumably closely related, genera such as Miscanthus,
Imperata, and Sorghum.
Species with awned lemmas are sometimes placed in a separate genus, Erianthus.
The most familiar species of Saccharum is S. officinarum, sugar cane.
The study by Hodkinson et al. (2002) suggests that some realignment is needed in both Saccharum and Miscanthus. Their study included only one North American taxon, S. brevibarbe var. contortum.
1 |
Spikelets
unawned, or with awns less than 5 mm long; anthers 3 (2) |
Spikelets awned, the awns 10-26 mm long;
anthers 2 (5) |
|
Spikelets with visible
awns, the awns 2-5 mm long ..... 6. S. ravennae |
|
Spikelets unawned, or the awns concealed
by the glumes (3) |
|
Lower glumes of sessile
spikelets pubescent ..... 9. S. bengalense |
|
Lower glumes of sessile spikelets mostly
glabrous, sometimes ciliate distally (4) |
|
Culms clumped, 2-5 cm
thick; rhizomes short; blades 20-60 mm wide ..... 8. S.
officinarum |
|
Culms solitary or few together, 0.6-2
cm thick; rhizomes elongate; blades 10-25 mm wide ..... 7. S.
spontaneum |
|
Awns spirally coiled
at the base (6) |
|
Awns straight
to curved at the base (7) |
|
Callus hairs 3-7 mm long,
equal to or shorter than the spikelets, white to brown; rachises glabrous
or sparsely pilose ..... 3. S. brevibarbe |
|
Callus hairs 9-14 mm long, exceeding
the spikelets, silvery or tinged with purple; rachises densely pubescent
..... 2. S. alopecuroides |
|
Callus hairs longer than
the spikelets; lowest panicle nodes densely pilose ..... 1. S.
giganteum |
|
Callus hairs absent or no more than equaling
the spikelets; lowest panicle nodes glabrous or sparsely pilose (8) |
|
Calluses glabrous or
with hairs to 2 mm long and exceeded by the spikelets; panicles 1-2.5
cm wide ..... 5. S. baldwinii |
|
Callus hairs 3-7 mm long, often equaling
the spikelets; panicles 3-10 cm wide (9) |
|
Awns flat basally; lower
lemmas of sessile spikelets not or indistinctly veined; upper lemmas 0.9-1
times as long as the lower lemmas ..... 3. S.
brevibarbe |
|
Awns terete basally; lower lemmas of
the sessile spikelets typically 3-veined; upper lemmas 0.7-0.8 times as
long as the lower lemmas ..... 4. S. coarctatum |
1. Saccharum giganteum (Walter) Pers.
Sugarcane Plumegrass
Plants rhizomatous. Culms 1-2.5 m; nodes sericeous, hairs
to 5 mm. Sheaths glabrate or glabrous; auricles absent; ligules
2-6 mm; blades usually 35-70 cm long, 8-30 mm wide, adaxial surfaces glabrous
or pilose. Peduncles 40-80 cm, pilose; panicles 6-15 cm wide, oblong
or lanceolate; rachises 15-30 cm, pilose; lowest nodes densely pilose;
primary branches 2-13 cm, ascending or appressed to the rachises; rame
internodes 2-5.5 mm, pilose. Sessile spikelets 4.2-6 mm long, 0.8-1.1
mm wide, straw-colored. Callus hairs (7)15-20(25) mm, longer than the spikelets,
straw-colored or brown; glumes usually glabrous; lower glumes smooth,
indistinctly 5-veined; lower lemmas 3-5 mm, without veins; upper lemmas
2.5-3.5 mm, 1-veined, entire; awns 12-26 mm, straight or curved, terete
basally; lodicule veins sometimes extending into hairlike projections; anthers
2. Pedicels 2.5-5 mm, pilose. Pedicellate spikelets similar to the
sessile spikelets, except frequently pilose. 2n = 30, 60, 90.
Saccharum giganteum grows in wet soils of bogs, swales, and swamps. Its
range extends from the eastern and southeastern United States to Central America.
It is a polymorphic, primarily chasmogamous species that intergrades morphologically
with the primarily cleistogamous S. trinii (Hack.) Renvoize in Central
America. The combination of long callus hairs and straight awns distinguishes
it from all other species of Saccharum in the Flora region. According to Hodkinson et al. (2002), this species is a hybrid and should be placed in Miscanthus.
2. Saccharum alopecuroides (L.) Nutt.
Silver Plumegrass
Plants rhizomatous. Culms 1-2.5 m; nodes hairy, occasionally
glabrate, hairs 7-12 mm. Sheaths mostly glabrous, ciliate distally; auricles
absent; ligules 1-3 mm; blades 30-60 cm long, 14-28 mm wide, glabrous
at maturity. Peduncles 40-60 cm, pilose; panicles 3-10 cm wide,
oblong to lanceolate; rachises 15-34 cm, densely pilose; lowest nodes
glabrous or sparsely pilose; primary branches 3-12 cm, appressed; rame
internodes 3-5 mm, pilose. Sessile spikelets 6-7 mm long, 1.1-1.4
mm wide, straw-colored; callus hairs 9-14 mm, exceeding the spikelets,
silvery or purple-tinged; lower glumes 5-veined, smooth; upper glumes
3-5-veined; lower lemmas 4.8-5.6 mm, without veins or 1-veined; upper
lemmas 4-4.6 mm, 1-veined, bifid, teeth 1.8-2 mm, ciliate; awns 14-20
mm, flattened and spirally coiled at the base; lodicule veins not extending
into hairlike projections; anthers 2. Pedicels 2.5-4 mm, pilose.
Pedicellate spikelets similar to the sessile spikelets, except frequently
pilose. 2n = 30.
Saccharum alopecuroides grows in damp woods, open areas, and field margins.
It is restricted to the southeastern United States. It is rare or non-existent
on the sandy coastal plain, and there are few specimens from southern Florida
and the higher elevations of the Appalachian Mountains. The combination of long
rhizomes, long silvery callus hairs, and spirally coiled awns distinguish S.
alopecuroides from all other species in the region.
3. Saccharum brevibarbe (Michx.) Pers.
Shortbeard Plumegrass
Plants rhizomatous. Culms 0.8-2.5 m; nodes glabrous or pubescent.
Sheaths not ciliate; auricles absent; ligules 1-2 mm; blades
usually 40-60 cm long, 7-25 mm wide, glabrous. Peduncles 45-75 cm, usually
glabrous, occasionally pubescent or minutely pilose; panicles 3-10 cm wide,
linear or oblong; rachises (10)30-50 cm, glabrous or sparsely pilose; lowest
nodes glabrous or sparsely pilose; primary branches 7-14 cm, appressed;
rame internodes 4-6 mm, with hairs. Sessile spikelets 6.5-10.5 mm
long, 1.2-1.5 mm wide, purple or straw-colored. Callus hairs 3-7 mm, from
shorter than to equaling the spikelets, white to straw-colored or brown; lower
glumes 5-veined, smooth basally, scabrous distally; lower lemmas 5.5-8
mm, not or indistinctly veined, initially entire, sometimes becoming bifid, teeth
2-2.5 mm; upper lemmas 5.5-8 mm, 0.9-1 times as long as the lower lemmas,
3-veined, entire or bifid; awns 10-22 mm, always flattened below, sometimes
spirally coiled; lodicule veins sometimes extending as hairlike projections;
anthers 2. Pedicels 3-4 mm, with hairs. Pedicellate spikelets
similar to the sessile spikelets. 2n = 60.
Saccharum brevibarbe grows only in the southeastern United States.
1 |
Awns 15-22
mm long, straight or sinuous at the base; upper lemmas of the sessile
spikelets entire at maturity ..... var. brevibarbe |
Awns 10-18 mm long, spirally coiled at
the base, usually with 2-4 coils; upper lemmas of the sessile spikelets
bifid at maturity, teeth about 2-2.5 mm long ..... var. contortum |
Saccharum brevibarbe (Michx.) Pers. var. brevibarbe
Upper lemmas of sessile spikelets entire at maturity;
awns 15-22 mm, straight or sinuous throughout.
Saccharum brevibarbe var. brevibarbe grows in the southeastern
coastal states and is common in central and southern Arkansas, eastern Oklahoma,
the piney woods region of eastern Texas, and northern Louisiana.
Saccharum brevibarbe var. contortum (Baldwin)
R.D. Webster
Upper lemmas of sessile spikelets initially entire, becoming bifid at
maturity, teeth about 2 mm; awns 10-18 mm, spirally coiled basally.
Saccharum brevibarbe var. contortum grows in moist, sandy pinelands
and open ground of the coastal plain, from Maryland to Florida and inland to
Tennessee and Oklahoma. Initially, the awns in var. contortum are not
coiled and the lemmas are entire but, as the spirals develop, they tear the
lemmas, creating the bifid apices.
4. Saccharum coarctatum (Fernald) R.D. Webster
Compressed Plumegrass
Plants cespitose, not or shortly rhizomatous. Culms 1-2.5 m; nodes
with 1-3 mm hairs. Sheaths glabrous; auricles 0.3-3 mm; ligules
1-2 mm; blades 15-40 cm long, 7-12 mm wide. Peduncles 35-45 cm,
glabrous; panicles 3-7 cm wide, linear to oblong; rachises 13-35
cm, glabrous or sparsely pilose; primary branches 5-12 cm, appressed; rame
internodes 3-6 mm, with hairs. Sessile spikelets 6-8 mm long, 0.9-1.2
mm wide, brown. Callus hairs 3-5 mm, from shorter than to equaling the
spikelets, white or straw-colored; lower glumes smooth or scabrous, 5-veined;
lower lemmas 5.8-7.5 mm, usually 3-veined; upper lemmas 4-5.5 mm,
0.7-0.8 times as long as the lower lemmas, 3-veined, entire; awns 16-26
mm, terete and straight to curving basally; lodicule veins extending into
hairlike projections to 0.6 mm long; anthers 2. Pedicels 3-5 mm,
sparsely and shortly pilose. Pedicellate spikelets similar to the sessile
spikelets. 2n = 60.
Saccharum coarctatum is common in wet, peaty or sandy soils of swales,
pond margins, and meadows of the coastal plain of the southeastern United States.
It is unusual in having lodicule veins that extend into hairlike projections up
to 0.6 mm long.
5. Saccharum baldwinii Spreng.
Narrow Plumegrass
Plants cespitose, rarely stoloniferous. Culms 0.9-1.8 m; nodes glabrous
or with hairs to 0.5 mm. Sheaths glabrous; ligules 1-3 mm, with
lateral lobes; blades 18-60 cm long, 5-12 mm wide, glabrous. Peduncles
30-40 cm, glabrous; panicles 1-2.5 cm wide, linear; lowest nodes
glabrous or sparsely pilose; rachises 10-35 cm, glabrous or sparsely pubescent;
primary branches 6-18 cm, appressed; rame internodes 3-5 mm, glabrous.
Sessile spikelets 7-10 mm long, 1.1-1.5 mm wide, brown. Callus hairs
absent or to 2 mm, shorter than the spikelets, straw-colored; lower glumes
scabrous, 5-veined; lower lemmas 6-8 mm, 2-veined; upper lemmas
0.9-1 times as long as the lower lemmas, 3-veined, entire; awns 17-24 mm,
terete, straight or curved at the base; lodicule veins extending into hairlike
projections; anthers 2. Pedicels 3-5 mm, glabrous. Pedicellate
spikelets similar to the sessile spikelets. 2n = 30.
Saccharum baldwinii commonly grows in sandy, shaded river and stream bottoms.
It occurs throughout the southeastern United States, but it is not as common as
other members of the genus, and is rare or completely absent from higher elevations
of the Appalachian Mountains.
6. Saccharum ravennae (L.) L.
Ravennagrass
Plants cespitose. Culms 2-4 m, glabrous; nodes
glabrous. Sheaths glabrous; auricles absent; ligules 0.6-1.1
mm; blades 50-100 cm long, 5-14 mm wide, glabrous. Peduncles 40-80
cm, glabrous; panicles lanceolate; rachises 30-70 cm, glabrous;
primary branches 6-20 cm, appressed or spreading; rame internodes
1-2 mm, with hairs. Sessile spikelets 4-6 mm long, 0.7-0.9 mm wide, straw-colored.
Callus hairs 4-6 mm, subequal to the spikelets, white; lower glumes
smooth, 4-5-veined; upper glumes 3-veined; lower lemmas 3-5 mm,
1-veined; upper lemmas subequal to the lower lemmas, without veins, entire;
awns 2-5 mm, flat, straight or curved at the base; lodicule veins
not extending into hairlike projections; anthers 3. Pedicels 1-3
mm, pubescent. Pedicellate spikelets similar to the sessile spikelets.
2n = 20.
Saccharum ravennae is native to southern Europe and western Asia. It
is grown as an ornamental in the Flora region, occasionally escaping
and persisting.
7. Saccharum spontaneum L.
Wild Sugarcane
Plants with long rhizomes. Culms 2-4 m tall, 0.6-2 cm thick, solitary
or few together. Sheaths usually glabrous; ligules 1.5-3 mm; blades
50-100 cm long, 10-25 mm wide, usually glabrous, markedly hirsute above the ligules.
Peduncles pilose; panicles 40-70 cm, narrowly oblong to widely ovate,
rachises 25-50 cm, densely pilose; primary branches 2.5-7 cm. Sessile
spikelets 3.5-7 mm. Callus hairs to 12 mm; glumes glabrous over
the back, ciliate toward the tip; lower lemmas about 3 mm; upper lemmas
subequal to the lower lemmas, entire; awns absent; anthers 3. Pedicels
1.5-3 mm, ciliate. Pedicellate spikelets similar to the sessile spikelets.
2n = 20, 24-30, 32, 36, 38, 40, 48-60, 64, 69.
Saccharum spontaneum is a weedy species, native to tropical Africa and
Asia, that is now established in Mesoamerica but not, so far as is known, in the
Flora region. It is listed as a noxious weed by the U.S. Department of
Agriculture, but it is grown in breeding programs as a source of potentially useful
genes for S. officinarum (sugar cane), with which
it readily hybridizes. Because of the potential economic damage of uncontrolled
hybridization between S. spontaneum and S. officinarum, the U.S.
Department of Agriculture should be notified of plants found growing outside a
controlled planting.
8. Saccharum officinarum L.
Sugarcane
Plants with short rhizomes. Culms 3-6 m tall,
2-5 cm thick, clumped, glabrous throughout or nearly so, lower internodes swollen.
Sheaths sometimes ciliate at the collar margins; auricles present;
ligules 2-3 mm; blades 70-150 cm long, 20-60 mm wide, usually
glabrous, occasionally with hairs on the adaxial surfaces. Peduncles
20-80 cm, glabrous; panicles 50-100 cm long, to 20 cm wide, lanceolate;
rachises 30-80 cm, glabrous; primary branches 10-25 cm, appressed
to spreading; rame internodes 3-6 mm, glabrous. Sessile spikelets
3-5 mm long, 0.8-0.9 mm wide, white to gray. Callus hairs 6-10 mm, exceeding
the spikelets, white; lower glumes glabrous, 2-4-veined; upper glumes
3-veined; lower lemmas 3-4.5 mm, 2-3-veined; upper lemmas without
veins, entire; awns absent; lodicule veins not extending into
hairlike projections; anthers 3. Pedicels 2-5 mm, glabrous. Pedicellate
spikelets similar to the sessile spikelets. 2n = 80.
Saccharum officinarum is native to tropical Asia and the Pacific islands.
It is cultivated for sugar production in various parts of the world, including
Texas, Louisiana, and Florida. It is also becoming popular as an ornamental
plant for gardens in warmer parts of the contiguous United States, and appears
to be established in some parts of the southeastern United States. A number
of different, clonally propagated color forms are available. It hybridizes with
S. spontaneum (see discussion above).
9. Saccharum bengalense Retz.
Tall Cane
Plants cespitose, not rhizomatous. Culms to 5 m, glabrous. Blades to
2 m long, 3-25 mm wide, flat or channeled, glaucous and scabrous. Panicles
20-90 cm, compact; primary branches 2-5 cm, considerably shorter than the
supporting branches; rame internodes hirsute, hairs to 7 mm. Sessile
spikelets 4-6 mm long, somewhat heteromorphic. Sessile spikelets: callus
hairs to 2.5 mm, white to gray; glumes equal; lower glumes membranous,
pubescent; upper glumes glabrous; lower lemmas oblong-elliptic, pubescent;
upper lemmas oblong-elliptic, ciliate on the margins, acute to shortly
awned; awns about 1.3 mm, not visible beyond the glumes; anthers
3. Pedicels shorter than the sessile spikelet. Pedicellate spikelets
pilose on the glumes, hairs 4-9 mm. 2n = 20, 22, 40, 60.
Saccharum bengalense is native from Iran to northern India. It is sometimes
cultivated as an ornamental in the Flora region.