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sourgrass

Asian crabgrass

Habit Plants perennial; cespitose, shortly rhizomatous, with knotty bases. Plants of indefinite duration; sometimes stoloniferous.
Culms

80-130 cm, erect, with densely villous cataphylls, branching from the lower and middle nodes.

with erect portion 10-85 cm, long-decumbent, rooting and branching at the lower nodes.

Sheaths

usually sparsely to densely papillose-hirsute, occasionally glabrous;

ligules 4-6 mm, usually lacerate, not ciliate;

blades 20-50 cm long, 10-17 mm wide, lax, smooth or scabridulous abaxially, scabridulous to scabrous adaxially.

with papillose-based hairs or the upper sheaths glabrous;

ligules 1-4 mm;

blades 3-14 cm long, 2-9 mm wide, mostly glabrous but the adaxial surfaces with papillose-based hairs basally.

Panicles

20-35 cm long, 2-10 cm wide, with numerous spikelike primary branches;

primary branches 10-15 cm, appressed to ascending at maturity, axes not wing-margined or with wings less than 1/2 as wide as the midribs;

internodes 3-4.5(6) mm (midbranch), bearing spikelets in unequally pedicellate pairs;

secondary branches rarely present;

pedicels not adnate to the branches;

shorter pedicels 0.7-2 mm;

longer pedicels 2.5-5 mm;

terminal pedicels 2-5 mm.

with (2)3-6 spikelike primary branches, these digitate or a few solitary branches below;

lowest nodes glabrous or with hairs less than 0.4 mm;

primary branches 6.5-21 cm long, 0.6-1.3 mm wide, axes winged, wings at least 1/2 as wide as the midribs, lower and middle portions bearing spikelets in unequally pedicellate pairs, pedicels not adnate to the branches;

secondary branches absent;

shorter pedicels about 0.2 mm;

longer pedicels to 2 mm.

Spikelets

5.5-8.2 mm (including pubescence), 4.2-5.9 mm (excluding pubescence), narrowly ovate, acuminate.

2.6-3.7 mm, spikelet pairs dimorphic in their pubescence and venation pattern of the lower lemmas.

Lower

glumes 0.6-0.8 mm;

upper glumes 3.5-4.5 mm, 3-5-veined, pubescent on the margins;

lower lemmas 4.1-5.7 mm (exceeded 1.5-5 mm by pubescence), narrowly ovate, 7-veined, pubescent between most, sometimes all, of the veins and on the margins, veins usually obscured by a dense covering of golden-brown hairs, hairs 3-6 mm, spreading at maturity, intercostal regions on either side of the midvein glabrous or pubescent with shorter, fine, white hairs, sometimes intermixed with the golden-brown hairs;

upper lemmas 3.2-4.5 mm, narrowly ovate, brown when immature, dark brown at maturity, acuminate;

anthers 1-1.2 mm.

glumes absent or to 0.9 mm, deltoid or bifid;

upper glumes 1.7-2.8 mm, 1/2 - 3/4 as long as the spikelets, 3-veined;

lower lemmas 7-veined, veins smooth;

lower lemmas of shortly pedicellate spikelets with 3 equally spaced, glabrous or shortly pubescent central veins, lemma margins and the region between the 2 lateral veins with appressed or spreading, 0.5-1 mm hairs;

lower lemmas of long-pedicellate spikelets with unequally spaced veins, midvein well-separated from the 3 lateral veins, lateral veins crowded together near the margins, lemma margins and the region between the 2 inner lateral veins hairy with appressed or strongly divergent, 1-2 mm hairs, sometimes also with longer, glassy yellow hairs;

upper lemmas of all spikelets usually yellow or gray, sometimes light brown, at maturity;

anthers 0.5-0.6 mm.

2n

= 36.

= 54, 72.

Digitaria insularis

Digitaria bicornis

Distribution
from FNA
AL; AZ; FL; IL; MS; TX; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA; IA; LA; MS; NC; SC; TX; VA; PR
[BONAP county map]
Discussion

Digitaria insularis grows in low, open ground of the southern United States, and extends to the West Indies, Mexico, and through Central America to Argentina.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Digitaria bicornis is a common species on the sandy coastal plain of the southeastern United States. Its range extends through Mexico to Costa Rica and northern South America, as well as to the West Indies. The Californian record reflects a 1926 collection; the species is not known to be established in the state.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 25, p. 370. FNA vol. 25, p. 380.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Digitaria Poaceae > subfam. Panicoideae > tribe Paniceae > Digitaria
Sibling taxa
D. abyssinica, D. arenicola, D. bakeri, D. bicornis, D. californica, D. ciliaris, D. cognata, D. didactyla, D. eriantha, D. filiformis, D. floridana, D. gracillima, D. hitchcockii, D. horizontalis, D. ischaemum, D. leucocoma, D. longiflora, D. milanjiana, D. nuda, D. patens, D. pauciflora, D. pubiflora, D. sanguinalis, D. serotina, D. setigera, D. simpsonii, D. texana, D. tomentosa, D. velutina, D. violascens
D. abyssinica, D. arenicola, D. bakeri, D. californica, D. ciliaris, D. cognata, D. didactyla, D. eriantha, D. filiformis, D. floridana, D. gracillima, D. hitchcockii, D. horizontalis, D. insularis, D. ischaemum, D. leucocoma, D. longiflora, D. milanjiana, D. nuda, D. patens, D. pauciflora, D. pubiflora, D. sanguinalis, D. serotina, D. setigera, D. simpsonii, D. texana, D. tomentosa, D. velutina, D. violascens
Synonyms Trichachne insularis
Name authority (L.) Mez ex Ekman (Lam.) Roem. & Schult.
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