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

920 POACEAE/ECHINOCHLOA
3. Inflorescence branches 3–7, usually 2(–3) cm or less long, without secondary branches;
spikelets 2–3 mm long, awnless, arranged in 4 regular rows, without papilla-based hairs;
leaf blades 3–6(–9) mm wide _____________________________________________________ E. colona
3. Inflorescence and spikelets without the above combination of characters; inflorescence
branches usually rebranched (but the secondary branches often short and inconspicuous),
often longer than 2 cm; spikelets often longer than 3 mm, often awned, in regular
rows or not so, sometimes with papilla-based hairs; leaf blades ca. 3–30 mm wide.
4. Lemma of lower floret with awn usually 1.5–6 cm long; inflorescences usually very large,
(10–)20–40 cm or more long and up to 10 cm thick; lemma of fertile (upper) floret without
a line of minute hairs across the base of the tip (use dissecting scope); rare glabrous-sheathed
form of this species _____________________________________________ E. walteri
4. Lemma of lower floret awnless or variously awned; inflorescences variable, often smaller;
lemma of fertile floret with a line of minute hairs across the base of the tip (use dissecting
scope); weedy species widespread and common in East TX.
5. Lemma of fertile (upper) floret obtuse to broadly acute, with a sharply differentiated,
withering, membranous tip; spikelets without papilla-based hairs __________________ E. crusgalli
5. Lemma of fertile floret acute to acuminate, tapering to a firm, stiff tip; spikelets usually
with some stout, papilla-based hairs ______________________________________ E. muricata
Echinochloa colona (L.) Link, (farmer, colonist, to inhabit), JUNGLE-RICE, AWNLESS BARNYARD
GRASS, SHAMA-MILLET. Culms 10–70 cm long; inflorescence branches not rebranched; spikelets
2–3 mm long, unawned, without papilla-based hairs. Low ground, disturbed areas; throughout
TX; widespread in s 1/2 of U.S., scattered elsewhere. Jul–Nov. Native of Old World tropics. Because
of disagreement over the Latin derivation, the specific epithet is sometimes spelled
“colonum” (Yatskievych 1999). We are following Gould (1975b), Jones et al. (1997), Kartesz (1999),
and Michael (2003) in using the spelling “colona.” Michael (2003) indicated that this spelling
reflects what was considered correct at the time of Linnaeus, who originally named the species.
This species is an important weed of rice as well as a number of other crops, and it is considered
by some sources to be among the world’s worst weeds (Zimdahl 1989; Holm et al. 1977). According
to Michael (2003), the “unbranched, rather widely-spaced panicle branches make this one
of the easier species of Echinochloa to recognize.” � I
Echinochloa crusgalli (L.) P. Beauv., (cockspur), BARNYARD GRASS, LARGE BARNYARD GRASS. Culms
30–100(–200) cm long; inflorescence axis erect or slightly drooping, the longer primary branches
with short, inconspicuous, secondary branches; spikelets (2.5–)2.8–4.4 mm long, without papillabased
hairs; lemma of lower floret awnless or with an awn to over 5 cm long; lemma of fertile
(upper) floret broadly ovate or broadly elliptic, apically obtuse to broadly acute, with a line of
minute hairs across the base of the tip (use dissecting scope; this and E. muricata are the only two
East TX Echinochloa species to display this distinctive but obscure character); 2n = 54. Low
ground, disturbed areas; throughout TX; s Canada and throughout the U.S. Jun–Oct. [Panicum
crusgalli L.] While the specific epithet is often spelled “crus-galli,” the correct spelling is without a
hyphen (Michael 2003), following the original usage by Linnaeus (1753). This species is apparently
introduced from the tropics and was reported from the U.S. by at least the early 1800s
(Maun & Barrett 1986). It is a cosmopolitan weed which now ranges from 53° N to 40° S (Maun
& Barrett 1986). Its success has been attributed to the production of large numbers of easily dispersed
seeds, the ability to develop rapidly, the ability for its seeds to lie dormant for long periods,
the capacity to flower under varying photoperiods, and relative resistance to herbicides
(Maun & Barrett 1986). It adversely affects a variety of crops and is considered by some sources
to be among the world’s worst weeds (Holm et al. 1977). While this is a variable species (e.g., awn
length), Michael (2003) did not consider the recognition of infraspecific taxa warranted. � I
Echinochloa crus-pavonis (Kunth) Schult. var. macra (Wiegand) Gould, (sp.: peacock spur; var.:
soften), GULF COCK-SPUR GRASS. Culms 30–100(–150) cm long; inflorescence axis stiffly erect;