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sourgrass

Habit Plants perennial; cespitose, shortly rhizomatous, with knotty bases. Plants perennial; cespitose.
Culms

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

to 100 cm, erect, not branching at the lower nodes;

nodes 1-2.

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 appressed hairs, lower sheaths densely hairy, upper sheaths sparingly hairy near the base, otherwise glabrous;

ligules 2-3 mm;

blades 10-40 cm long, to 3 mm wide, usually flat, involute when dry.

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 branches on 4-6 cm rachises;

primary branches 20-25 cm long, axes triquetrous, not winged;

primary branches bearing spikelets in unequally pedicellate groups of 3(-5) on the basal 1/2;

secondary branches rarely present, longer pedicels often adnate to the branch axes basally.

Spikelets

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

2.2-2.5 mm long, 0.8 mm wide, elliptic, acute.

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;

upper glumes 3-veined, margins and intercostal regions with long, glandular-tipped hairs;

lower lemmas 7-veined, margins and the region between the 2 inner marginal veins with long glandular hairs;

upper lemmas light to dark brown at maturity, striate, apiculate.

2n

= 36.

= unknown.

Digitaria insularis

Digitaria filiformis

Distribution
from FNA
AL; AZ; FL; IL; MS; TX; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
from USDA
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 leucocoma is known only from high pine-lands near Lake Ella, Lake County, Florida. It has been treated in the past as a synonym of D. filiformis var. villosa.

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

Source FNA vol. 25, p. 370. FNA vol. 25, p. 366.
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. didactyla, D. eriantha, D. filiformis, D. floridana, D. gracillima, D. hitchcockii, D. horizontalis, D. insularis, D. ischaemum, 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 (Nash) Urb.
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