26.02   SACCHARUM L.
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.


SELECTED REFERENCES Hodkinson, T.R., M.W. Chase, M.D. Lledo, N. Salamin, and S.A. Renvoize. 2002. Phylogenetics of Miscanthus, saccharum and related genera (Saccharinae, Andropogoneae,Poaceae) based on DNA sequences sfrom ITS nuclear ribosomal DNA and plastid trnL intron and trnL-F intergenic spaces. Journal of Plant Research 115:381-392 [doi 10.1007/s10265-002-0049-3]; Webster, R.D. and R.B. Shaw. 1995. Taxonomy of the North American species of Saccharum (Poaceae: Andropogoneae). Sida 16:551-580.

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)
2
Spikelets with visible awns, the awns 2-5 mm long ..... 6. S. ravennae
Spikelets unawned, or the awns concealed by the glumes (3)
3
Lower glumes of sessile spikelets pubescent ..... 9. S. bengalense
Lower glumes of sessile spikelets mostly glabrous, sometimes ciliate distally (4)
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
5
Awns spirally coiled at the base (6)
Awns straight to curved at the base (7)
6
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
7
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)
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)
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.