Vascular Plants of North Carolina
Account for Seaside Three-awn - Aristida tuberculosa   Nuttall
Members of Poaceae:
Members of Aristida with account distribution info or public map:
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Section 5 » Order Cyperales » Family Poaceae
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DistributionMostly in the Sandhills; scattered in the southwestern Coastal Plain, and rare in the lower Piedmont of Anson County.

Seacoast from NH to VA; inland from NC to northern FL and southern MS (also coastal in MS); disjunct inland to northern Mississippi River drainage sandbars and southern Lake Michigan dunes.
AbundanceFrequent to common in the Sandhills, uncommon in the Coastal Plain southeast to Brunswick County; rare in the lower Piedmont. Plants often are numerous where found.
HabitatXeric roadsides, powerline clearings, other clearings, edges of pine-oak scrub; usually where the soil is relatively loose.
PhenologyFlowering and fruiting August-October.
IdentificationDespite its common name, here in NC Seaside Three-awn occurs only inland. The plants grow erect, 1.5-2.5 feet tall, with an open inflorescence in the upper 1/4 to 1/3 of the stem. The basal portions of the 3 awns are twisted together for about 8-15 mm; the free portions are 30-40 mm (i.e., to about 1.5 inches long). These very long awns, twisted near the base, can be quite conspicuous and easily catch one's attention.
Taxonomic CommentsNone

The genus Aristida is most notable for the 3 hairlike awns which project from each floret. The central awn is almost always thicker than the other 2 awns. The awns may stand erect, especially during the early flowering period, but in most species eventually are bent parallel to the ground. In some species, only the central awn is bent, while the other 2 remain erect. In some species, all awns are the same length, while in other species the central awn is distinctly longer. The awns have tiny barbs which catch onto hair and fur, and florets will even hitch a ride up the inside of your pants!
Other Common Name(s)Seabeach Needlegrass, Beach Three-awn
State RankS3
Global RankG5
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US Status
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B.A. SorrieSandhills Game Land, xeric side of sand road, Sept 2014. RichmondPhoto_natural

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