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

ERIONEURON/POACEAE
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Shaw and Smeins (1983) concluded that it represents swollen or expanded internode tissue
fused with the much-reduced lower glume. Thompson et al. (1990), however, found that it lacks
vascular tissue, is formed entirely of parenchymatous tissue, and that glume tissue is not involved.
They concluded that it is “formed by a proliferation of the ground tissue at the spikelet
base.” Davidse (1987a) suggested a possible function—the cup-shaped structure might contain
lipids and function as an elaiosome to attract ants that would act as dispersal agents for the
seeds. (Greek: erion, wool, and chloa, grass, in reference to the densely hairy pedicels and spikelets
of the type species—Shaw & Webster 1981) (subfamily Panicoideae, tribe Paniceae)
REFERENCES: Shaw & Smeins 1979, 1981, 1983; Shaw & Webster 1987; Thompson et al. 1990;
Crins 1991; Arriaga 2000; Shaw et al. 2003.
1. Pedicels with long silky hairs ca. half as long as the spikelets or longer; inflorescence branches
(racemes) not or only scarcely overlapping each other; leaf blades 0.5–4 mm wide; lemma of
perfect floret awnless or with a minute awn tip less than 0.4 mm long _________________________ E. sericea
1. Pedicels glabrous or with only very short pubescence; inflorescence branches overlapping each
other; leaf blades 2–10(–13) mm wide; lemma of perfect floret with an awn 0.4–1.5 mm long.
2. Leaf blades glabrous or scabrous on lower surface; plants perennial (but may flower first year
and appear annual); spikelets (4–)4.5–5.7 mm long, typically paired (but becoming solitary
toward tip of inflorescence branch); species known in East TX only from s portion of area
_____________________________________________________________________________ E. punctata
2. Leaf blades pubescent on lower surface; plants annual; spikelets 3.5–4.5(–5) mm long, solitary
(occasionally paired at base of inflorescence branch); species widespread in East TX ________ E. contracta
Eriochloa contracta Hitchc., (contracted), PRAIRIE CUP GRASS. Annual 15–75(–100) cm tall, often with
many culms, forming bushy clumps; leaf sheaths and blades (at least the lower ones) often rather
densely soft-pubescent; leaf blades 2–8 mm wide; lemma of perfect floret with awn 0.4–1.1 mm
long; spikelets mostly solitary. Roadsides, ditches, disturbed areas; in East TX mainly Blackland
Prairie, but widespread in TX; se Canada (Ont.) and sc and sw U.S., scattered elsewhere. May–Oct.
Eriochloa punctata (L.) Desv. ex Hamilton, (spotted), LOUISIANA CUP GRASS, EVERLASTING GRASS.
Perennial, rhizomatous, 30–150 cm tall; leaf sheaths and blades usually glabrous or blades scabrous;
leaf blades (2–)4–10(–13) mm wide; lemma of perfect floret with awn 0.6–1.5 mm long;
spikelets mostly paired. Ditches and other moist areas; Brazos and Harris (TAES) cos.; mainly
Gulf Prairies and Marshes and South TX Plains; LA and TX. Mar–Dec. [Milium punctatum L.]
This species is the least common member of the genus in East TX. It is considered a significant
weed in some areas (presumably where not native) by Watson and Dallwitz (1992).
Eriochloa sericea (Scheele) Munro ex Vasey, (silky), TEXAS CUP GRASS, SILKY CUP GRASS. Perennial
with short rhizomes but tufted, 30–130 cm tall, rather densely soft-pubescent; spikelets 4–5
mm long, solitary; lemma of perfect floret awnless or with a minute awn tip less than 0.4 mm
long. Prairies, open thickets, roadsides, calcareous clays or clay loams; widespread in w part of
East TX from Leon (BRIT) and Grimes (Turner et al. 2003) cos. w; w portion of East TX w to
Rolling Plains and s to Edwards Plateau, South TX Plains, and Gulf Prairies and Marshes; CO,
KS, NE, OK, and TX. May–Oct. This is a secondary member of the original prairie. It is reported
to be good forage but does not withstand grazing; it is said to persist in overgrazed pastures only
under the protection of shrubs (Hatch et al. 1999).
ERIONEURON Nash WOOLLY GRASS, FLUFF GRASS
AA New World C4 genus of 3 species (Valdés-Reyna & Hatch 1997; Valdés-Reyna 2003b);
similar to and previously included in Tridens. Seedlings “appear to have a shaggy, white-villous
‘indumentum,’ but this is composed of a myriad of small, water-soluble crystals” (Valdés-
Reyna 2003b). The monotypic genus Dasyochloa of the sw U.S. and n Mexico has at times been