Cenchrus tribuloides |
Cenchrus longispinus |
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dune sandbur, sanddune sandbur |
burgrass, cenchrus à épines longues, field sandbur, long-spine sandbur, mat sandbur, sandbur |
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Habit | Plants annual. | Plants annual; tufted. |
Culms | 10-70 cm, decumbent, branching and rooting at the lower nodes. |
20-90 cm, sometimes decumbent, often with many branches arising from the base. |
Sheaths | compressed, glabrous or pubescent; ligules 1-2.1 mm; blades 2-14 cm long, 3-14.2 mm wide. |
strongly compressed-keeled; ligules 0.6-1.8 mm; blades 4-27 cm long, 1.5-5(7.5) mm wide, adaxial surfaces scabrous or sparsely pilose. |
Panicles | 2-8.2 cm; fascicles 9-16 mm long, 4-8 mm wide, imbricate, ovoid, densely pubescent; bristles 15-43; outer bristles usually present, flattened or terete; inner bristles 4-8 mm long, 1.2-3 mm wide, fused for at least 1/2 their length, forming a distinct cupule, the distal portions diverging at irregular intervals from the cupule, stramineous or purple. |
1.5-8(10) cm; fascicles 8.3-11.9 mm long, 3.5-6 mm wide, somewhat globose, medium- to short-pubescent; bristles 45-75; outer bristles numerous, shorter and thinner than the inner bristles, imbricate, mostly terete, reflexed; inner bristles 3.5-7 mm long, 0.5-0.9(1.4) mm wide at the base, irregularly placed, fused for 1/2 their length or more, forming a distinct cupule, the distal portions diverging at irregular intervals from the cupule, often grooved along the margins, purple-tinged. |
Spikelets | 1(2) per fascicle, 6-8.8 mm. |
2-3(4) per fascicle, (4)5.8-7.8 mm. |
Lower glumes | 1-4 mm; upper glumes 4.9-6.8 mm, 3-7-veined; lower lemmas 5.5-7.5 mm, 3-7-veined, enclosing the palea; upper lemmas 6-8.7 mm; anthers 0.8-2.8 mm. |
0.8-3 mm; upper glumes 4-6 mm, 3-5-veined; lower florets often staminate; lower lemmas 4-6.5 mm, 3-7-veined; anthers 1.5-2 mm; upper lemmas 4-7(7.6) mm; anthers 0.7-1 mm, seemingly not well-developed at anthesis. |
Caryopses | 2.6-4 mm long, 2.2-3.1 mm wide, ovoid-elliptic. |
2-3.8 mm long, 1.5-2.6 mm wide, ovoid. |
2n | = 34. |
= 34 (38). |
Cenchrus tribuloides |
Cenchrus longispinus |
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Distribution |
AL; CT; DE; FL; GA; LA; MA; MD; ME; MS; NC; NJ; NY; PA; SC; VA; VT; HI
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AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; BC; ON; QC
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Discussion | Cenchrus tribuloides grows in moist, sandy dunes and is restricted to the eastern United States. It differs from C. spinifex in its larger spikelets and smaller number of spikelets per fascicle, and from C. longispinus in its densely pubescent fascicles, fewer bristles, and wider inner bristles. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cenchrus longispinus grows in sandy woods, fields, and waste ground in southern Canada and the contiguous United States. Its range extends southwards to Venezuela. It is often confused with C. spinifex and C. tribuloides; see discussion under those species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 25, p. 534. | FNA vol. 25, p. 534. |
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Cenchrus | Poaceae > subfam. Panicoideae > tribe Paniceae > Cenchrus |
Sibling taxa | ||
Synonyms | C. carolinianus | |
Name authority | L. | (Hack.) Fernald |
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