Digitaria insularis |
Digitaria californica |
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sourgrass |
Arizona cottontop |
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Habit | Plants perennial; cespitose, shortly rhizomatous, with knotty bases. | Plants perennial; cespitose, neither rhizomatous nor stoloniferous. |
Culms | 80-130 cm, erect, with densely villous cataphylls, branching from the lower and middle nodes. |
40-100 cm, erect, sometimes geniculate, not rooting, 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. |
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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 4-10 spikelike primary branches on 5-10 cm rachises, rarely with secondary branches; primary branches 3-6 cm, appressed to ascending, axes not wing-margined; internodes 2-5.5 mm (midbranch), bearing spikelets in unequally pedicellate pairs; secondary branches rarely present; pedicels not adnate to the branch axes; shorter pedicels 0.1-0.3 mm; longer pedicels 1-2 mm; terminal pedicels of branches 1.7-6(7) mm. |
Spikelets | 5.5-8.2 mm (including pubescence), 4.2-5.9 mm (excluding pubescence), narrowly ovate, acuminate. |
homomorphic, (3.7)4-7.5 mm (including pubescence), 3-5.4 mm (excluding pubescence). |
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. |
0.4-0.6 mm; upper glumes 2.5-5.1 mm (excluding pubescence), narrower than the upper florets, 3-veined, densely villous, hairs 1.5-5 mm, silvery-white to purple, widely divergent at maturity; lower lemmas 2.7-5 mm (excluding pubescence), pubescence exceeding the upper florets by 2.2-4 mm, 7-veined, veins unequally spaced, only the 3 or 5 central veins visible, margins and outer lateral veins densely pubescent, hairs 1.5-5 mm, silvery-white to purple, widely divergent at maturity, intercostal regions glabrous, apices attenuate (acuminate); upper lemmas 2.5-3.4 mm, ovate-lanceolate, brown to dark brown, acuminate. |
Caryopses | 1.3-2 mm. |
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Basal | sheaths villous; upper sheaths glabrous, densely villous or densely tomentose, or sparsely to densely hairy, with papillose-based hairs; ligules (1)1.5-6 mm, entire or lacerate, not ciliate; blades 2-12(18) cm long, 2-5(7) mm wide, glabrous or the adaxial surfaces sparsely to densely villous or tomentose. |
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2n | = 36. |
= 36, 54, 70, 72. |
Digitaria insularis |
Digitaria californica |
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Distribution |
AL; AZ; FL; IL; MS; TX; HI; PR; Virgin Islands
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AZ; CA; CO; NM; OK; TX
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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 californica grows on plains and open ground from Arizona, southern Colorado, and Oklahoma through Mexico and Central America to South America. The name reflects the fact that the first collection was made in Baja California, Mexico. Plants in the Flora region belong to D. californica (Benth.) Henrard var. californica. They differ from those of D. californica var. villosissima Henrard in having densely villous, rather than densely tomentose, leaves. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 25, p. 370. | FNA vol. 25, p. 368. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Trichachne insularis | Trichachne californica |
Name authority | (L.) Mez ex Ekman | (Benth.) Henrard |
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