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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
from FNA
AL; CT; DE; FL; GA; LA; MA; MD; ME; MS; NC; NJ; NY; PA; SC; VA; VT; HI
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; FL; GA; MS; PR
[BONAP county map]
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
C. biflorus, C. brownii, C. echinatus, C. gracillimus, C. longispinus, C. myosuroides, C. spinifex
C. biflorus, C. brownii, C. echinatus, C. longispinus, C. myosuroides, C. spinifex, C. tribuloides
Name authority L. Nash
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