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.