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

884 POACEAE/DICHANTHELIUM
Asian taxa in a separate genus, Neomolinia Honda (e.g., Tsvelev 1989, who recognized Neomolinia
as having 5 species). Subfamilial classification of Diarrhena is problematic, with some authorities
putting it in the Pooideae and others in the Bambusoideae (Brandenburg et al. 1991a); recent
evidence suggests the appropriate placement is in the Pooideae (Grass Phylogeny Working
Group 2001). The following key is from Brandenburg et al. (1991a). (Greek: di, two or twice, and
arrhen, male, from the two stamens) (subfamily Pooideae, tribe Diarrheneae)
REFERENCES: Koyama & Kawano 1964; Macfarlane & Watson 1980; Tsvelev 1989; Brandenburg
et al. 1991a; Brandenburg 2003, ined.
1. Callus on all mature lemmas except first [= lowest] pubescent; lemmas widest below the middle
and gradually tapering into a cusp at apex, the lemma of first floret 7.1–10.8 mm long; mature
fruits 1.3–1.8 mm broad, gradually tapering into a broad, blunt beak ______________________ D. americana
1. Callus on all mature lemmas glabrous; lemmas widest near or above the middle and � abruptly
contracted into cusp at apex, the lemma of first floret 4.6–7.5 mm long; mature fruits 1.8–2.5 mm
broad, abruptly contracted into a bottlenose-shaped beak ________________________________ D. obovata
Diarrhena americana P. Beauv., (of America), AMERICAN BEAKGRAIN. Culms ca. 0.6–1.3 m tall; leaf
sheaths often hairy, sometimes only near summit; ligule a membranous collar 0.5–1.8 mm long;
leaf blades 7–20 mm wide; inflorescences 9–30 cm long, with 4–23 spikelets; spikelets 10–20
mm long; lemmas usually 5.3–10.8 mm long, glabrous to minutely scabrous; anthers (1.7–)2–
2.9(–3.5) mm long. Woodlands; this species has long been reported from TX based on a
Reverchon collection from Dallas (Mahler 1988). However, the Dallas material is of the recently
named, related species, D. obovata (Brandenburg et al. 1991a). Hatch et al. (1990) reported D.
americana from the Pineywoods, but it is not known which species this citation represents; no
county distribution map is provided. Diarrhena americana, native to the e U.S., is known from
e OK but is unconfirmed for TX (Brandenburg et al. 1991a). It is included here to help clarify recent
changes in the taxonomy of the genus. Summer–fall.
Diarrhena obovata (Gleason) Brandenburg, (obovate, inversely ovate), HAIRY BEAKGRAIN. Culms
ca. 0.5–1.3 m tall; leaf sheaths usually glabrous; ligule 0.2–1 mm long; leaf blades 6–18 mm wide;
inflorescences 5–30 cm long, with 4–33 spikelets; spikelets 7–17 mm long; lemmas 4.6–7.5 mm
long, glabrous; anthers 1.4–2 mm long. Woodlands; Dallas Co. (Mahler 1988; Brandenburg et al.
1991a), collected by Reverchon in June 1874, in “rich woods, Buzzards Spring” (now in an e Dallas
residential section), not found in TX since that time (Mahler 1988; cited as D. americana);
the Dallas Co. location is the only one cited for TX by Brandenburg et al. (1991a); se Canada
(Ont.) and e U.S. from NY s to VA w to SD and TX. Summer–fall. [D. americana var. obovata
Gleason] While not officially designated as such (e.g., TOES 1993; Carr 2002d; Poole et al. 2002),
given its limited distribution in the state, we consider this species to be of conservation concern
in TX. �
DICHANTHELIUM (Hitchc. & Chase) Gould
ROSETTE GRASS, PANIC GRASS
Annuals or perennials with or without rhizomes; plants with basal tuft or rosette of leaves
present, these shorter and wider than those of the culms, produced from fall to spring and persistent;
ligule usually a membrane, often ciliate or with a fringe of hairs; panicles terminal on
mostly simple culms, produced in spring and early summer, a second crop of more numerous
lateral or basal panicles (often of cleistogamous spikelets) produced in late summer or fall (descriptions
are of spring phase only, autumnal phase often appears quite different); spikelets
awnless, 2-flowered, the lower floret sterile or staminate, the upper floret perfect; glumes usually
both present, the lower typically shorter; lemma of lower floret resembling upper glume;
lemma of upper (perfect) floret firm to hardened, shiny and glabrous with margins inrolled.