Digitaria insularis |
Digitaria ciliaris |
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sourgrass |
fingergrass, Henry's crabgrass, kukaepua'a, saulangi, smooth crabgrass, southern crab grass, tropical crabgrass |
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Habit | Plants perennial; cespitose, shortly rhizomatous, with knotty bases. | Plants annual or of indefinite duration. | ||||
Culms | 80-130 cm, erect, with densely villous cataphylls, branching from the lower and middle nodes. |
10-100 cm long, erect portion 30-60 cm, long-decumbent, rooting and branching at the decumbent nodes, sparingly branched or unbranched from the upper nodes; nodes 2-5, glabrous. |
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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; ligules 2-3.5 mm, erose; blades 1.5-14.4(18.9) cm long, 3-9 mm wide, flat, glabrous, a few scattered papillose-based hairs at the base of the adaxial surfaces (occasionally over the whole adaxial surface), usually also scabrous on both surfaces. |
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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 2-10 spikelike primary branches, these digitate or in 1-3 whorls on rachises to 2 cm; lowest panicle nodes with hairs more than 0.4 mm; primary branches 3-24 cm long, 0.6-1.2(2) mm wide, glabrous or with less than 1 mm hairs, axes wing-margined, wings at least 1/2 as wide as the midribs, lower and middle portions of the branches bearing spikelets in unequally pedicellate pairs; secondary branches absent; shorter pedicels 0.5-1 mm; longer pedicels 1.5-4 mm. |
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Spikelets | 5.5-8.2 mm (including pubescence), 4.2-5.9 mm (excluding pubescence), narrowly ovate, acuminate. |
(2.7)2.8-4.1 mm long, homomorphic. |
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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 0.2-0.8 mm, acute; upper glumes (1.2)1.5-2.7 mm, about 2/3 to almost as long as the spikelet, 3-veined, margins and apices pilose; lower lemmas 2.7-4.1 mm, 7-veined, veins unequally spaced, outer 3 veins crowded together near each margin, well-separated from the midvein, usually smooth, occasionally the lateral veins scabridulous on the distal 1/3 margins and regions between the 2 inner lateral veins hairy, hairs 0.5-1 mm (rarely glabrous), sometimes also with glassy yellow hairs between the 2 inner lateral veins, these more common on the upper spikelets; upper lemmas 2.5-4 mm, glabrous, yellow, tan, or gray when immature, becoming brown, often purple-tinged (occasionally completely purple) at maturity; anthers 0.6-1 mm. |
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2n | = 36. |
= 54. |
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Digitaria insularis |
Digitaria ciliaris |
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Distribution |
AL; AZ; FL; IL; MS; TX; HI; PR; Virgin Islands
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AL; AR; AZ; CA; CT; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MO; MS; NC; NE; NJ; NM; NY; OH; OK; PA; SC; TN; TX; UT; VA; HI; PR; Virgin Islands
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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 ciliaris is a weedy species, found in open, disturbed areas in most warm-temperate to tropical regions, primarily in the eastern United States. It is particularly abundant in the Southeast. So far as is known, the two varieties distinguished in the following key do not differ in any other characters. They are recognized here pending further study. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 25, p. 370. | FNA vol. 25, p. 382. | ||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Digitaria | Poaceae > subfam. Panicoideae > tribe Paniceae > Digitaria | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Trichachne insularis | |||||
Name authority | (L.) Mez ex Ekman | (Retz.) Koeler | ||||
Web links |