Cenchrus tribuloides |
Cenchrus gracillimus |
|
---|---|---|
dune sandbur, sanddune sandbur |
slender sandbur |
|
Habit | Plants annual. | Plants perennial; sometimes forming dense clumps. |
Culms | 10-70 cm, decumbent, branching and rooting at the lower nodes. |
20-80 cm, wiry. |
Sheaths | compressed, glabrous or pubescent; ligules 1-2.1 mm; blades 2-14 cm long, 3-14.2 mm wide. |
shorter than the internodes, keeled, usually glabrous, rarely sparsely pilose; ligules 0.2-0.6 mm; blades 5-25 cm long, 1-3.5 mm wide, stiff, adaxial surfaces usually glabrous, smooth or scabrous. |
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. |
2-6(6.8) cm; rachis internodes 2-4 mm; fascicles 5-13 mm long, 2-4 mm wide, not imbricate, ovoid, glabrous; outer bristles sometimes present, flattened; inner bristles less than 30, 3.2-6 mm long, 0.2-1 mm wide at the base, in more than 1 whorl, fused for at least 1/2 their length into a distinct cupule, diverging at irregular intervals from the cupule, somewhat flattened, spreading, purple-tipped at maturity. |
Spikelets | 1(2) per fascicle, 6-8.8 mm. |
1-3 per fascicle, 4-7 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. |
1.4-3.1 mm; upper glumes 3.2-5.4 mm, 3-5-veined; upper lemmas 4-6 mm, 3-5-veined; upper florets 3.9-6.5 mm; anthers 0.9-1.9 mm. |
Caryopses | 2.6-4 mm long, 2.2-3.1 mm wide, ovoid-elliptic. |
1.8-3 mm long, 1-1.5 mm wide, ovoid-elliptic. |
2n | = 34. |
= 34. |
Cenchrus tribuloides |
Cenchrus gracillimus |
|
Distribution |
AL; CT; DE; FL; GA; LA; MA; MD; ME; MS; NC; NJ; NY; PA; SC; VA; VT; HI
|
AL; FL; GA; MS; PR |
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 gracillimus grows in sandy soils of open pinelands, wet prairies, and river flats of the southeastern United States and the West Indies. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 25, p. 534. | FNA vol. 25, p. 533. |
Parent taxa | Poaceae > subfam. Panicoideae > tribe Paniceae > Cenchrus | Poaceae > subfam. Panicoideae > tribe Paniceae > Cenchrus |
Sibling taxa | ||
Name authority | L. | Nash |
Web links |