keys to the vascular plants of east texas - Botanical Research ...

1044 POACEAE/SACCHARUM
5. Callus hairs conspicuous, 3–6.5 mm long; main branches of inflorescence pubescent,
ascending, the inflorescence usually 3–10 cm wide.
6. Awn of lemma of fertile floret flattened at base; lemma of sterile (= lower) floret without
distinct veins; both florets of a spikelet nearly equal in size, the lemma of fertile
floret 0.9–1 times the length of the lemma of sterile floret; leaf sheaths without distinct
auricles __________________________________________________________ S. brevibarbe
6. Awn of lemma of fertile floret terete (= rounded) at base; lemma of sterile floret typically
with 3 veins; florets of a spikelet unequal in size, the lemma of fertile floret only
0.7–0.8 times the length of the lemma of sterile floret; leaf sheaths with minute auricles
0.3–1 mm long ___________________________________________________ S. coarctatum
Saccharum alopecuroides (L.) Nutt., (resembling Alopecurus–foxtail grass), SILVER PLUME GRASS.
Plant rhizomatous, culms 1–2.5 m tall, with white pilose hairs usually 7–12 mm long on the
nodes (can be glabrous at maturity); leaf sheaths without auricles; ligule 1–3 mm long; leaf
blades 14–28 mm wide, glabrous at maturity except for white pilose hairs at base; callus hairs
longer than spikelet, ca. 9–14 mm long, silvery or with purplish tinge; spikelets 6–7 mm long;
awn of lemma of fertile floret flattened and spiraled at base, geniculate, 14–20 mm long; 2n =
30 (Webster 1994). Dry clay slopes; widespread in the Pineywoods; e US from NJ s to FL w to IL,
OK, and TX. Late summer–fall. [Erianthus alopecuroides (L.) Elliott, Erianthus alopecuroides
var. hirsutus Nash, Erianthus divaricatus (L.) Hitchc., Erianthus tracyi Nash] This species is
most similar morphologically to S. giganteum but is distinguished by the awn of the lemma of
fertile floret being spiraled (Webster & Shaw 1995). While the specific epithet is sometimes
spelled “alopecuroideum,” the correct spelling is alopecuroides (Webster 2003).
Saccharum baldwinii Spreng., (probably for William Baldwin, 1779–1819, physician, botanist,
and plant collector in the se U.S. and South America), NARROW PLUME GRASS. Plant from a
knotty base; culms 0.9–1.8 m tall, the nodes glabrous or with minute hairs ca. 0.5 mm long; leaf
sheaths with minute ovate auricles ca. 1 mm long; ligule 1–3 mm long; leaf blades 5–12 mm
wide, the upper surface glabrous; callus glabrous or with straw-colored hairs much shorter
than spikelets (2 mm or less long); spikelets 7–10 mm long; awn of lemma of fertile floret terete
at base, not spiraled, straight or nearly so, 17–24 mm long; 2n = 30 (Webster 1994). Shaded river
and stream bottoms; widespread in the Pineywoods; also n margin of Gulf Prairies and
Marshes; se U.S. from MD s to FL w to MO, OK, and TX. Sep–Nov. [Erianthus strictus Elliott, Saccharum
strictum (Elliott) Elliott ex Nutt.] This species is morphologically similar to S.
coarctatum (Webster & Shaw 1995).
Saccharum brevibarbe (Michx.) Pers. (short-bearded), BENT-AWN PLUME GRASS, BEARD GRASS. Plant
rhizomatous, culms 0.8–2.5 m tall, the nodes glabrous or with hairs; leaf sheaths without auricles;
ligule 1–2 mm long; leaf blades 7–25 mm wide, glabrous; callus hairs shorter than the spikelet,
3–6.5 mm long, white to straw-colored; spikelets 6.5–10 mm long; awn of lemma of fertile floret
flattened at base, either spiraled or not spiraled (depending on variety), 10–22 mm long; 2n = 60
(Webster 1994). Usually moist, sandy soils, but varying from well-drained to seasonally
flooded sites; widespread in Pineywoods and n Post Oak Savannah; also n edge of Gulf Prairies
and Marshes; the maps in Turner et al. (2003) and the one presented here do not separate varieties.
Aug–Nov. This species is most similar to S. coarctatum (Webster & Shaw 1995). Webster and
Shaw (1995) indicated that the 2 varieties of S. brevibarbe (previously often treated as separate
species) are distinguished only by the lemma awn and associated characters. They further
noted that intermediates between the varieties are not uncommon and that combining them into
one species “was considered the most appropriate way to reflect the biological relationship.”
1. Awn of lemma of fertile floret not spiraled at base, 10–18 mm long; lemma of fertile floret entire
____________________________________________________________________________ var. brevibarbe