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sourgrass

blue couch, crabgrass

Habit Plants perennial; cespitose, shortly rhizomatous, with knotty bases. Plants perennial; stoloniferous and rhizomatous, mat-forming.
Culms

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

15-40(63) cm, rooting and branching from 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.

densely to sparsely hairy, with 3-5 mm papillose-based hairs;

ligules 1-1.5 mm;

blades 2.5-7 cm long, 1-3 mm wide, flat or folded, usually glabrous, green to bluish-green.

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 2-4 spikelike primary branches digitately arranged;

primary branches 2-7 cm, axes wing-margined, wings at least 1/2 as wide as the midribs, spikelets somewhat imbricate, in unequally pedicellate pairs;

secondary branches rarely present;

pedicels not adnate to the branches;

shorter pedicels 1-1.5 mm;

longer pedicels 2-3 mm;

axillary panicles not present.

Spikelets

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

homomorphic, 2-2.8 mm long, about 0.8 mm wide.

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 to 0.3 mm, triangular;

upper glumes from 1/2 - 3/4 as long as the spikelets, 3-veined, pilose on the margins and sometimes between the veins;

upper lemmas equaling the spikelets, prominently 7-veined, veins equally spaced, margins and sometimes the intercostal regions pilose, hairs 0.3-0.5 mm;

upper lemmas slightly shorter than the lower lemmas, almost smooth, gray, sometimes purple-tinged, at maturity.

2n

= 36.

= unknown.

Digitaria insularis

Digitaria didactyla

Distribution
from FNA
AL; AZ; FL; IL; MS; TX; HI; PR; Virgin Islands
[WildflowerSearch map]
[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.)

A native of Africa, Digitaria didactyla is often cultivated as a lawn grass in tropical and subtropical regions. It has been grown experimentally in Florida, but is not otherwise known from the Flora region.

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

Source FNA vol. 25, p. 370. FNA vol. 25, p. 376.
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. bicornis, D. californica, D. ciliaris, D. cognata, 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 Willd.
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