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Forked Threeawn

Aristida basiramea Vasey

Physical Description

provided by USDA PLANTS text
Annuals, Terrestrial, not aquatic, Rhizomes present, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stems branching above base or distally at nodes, Stem internodes solid or spongy, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath hairy, hispid or prickly, Leaf sheath or blade keeled, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades very narrow or filiform, less than 2 mm wide, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence lateral or axillary, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence with 2-10 branches, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequ al, Glumes equal to or longer than adjacent lemma, Glumes awned, awn 1-5 mm or longer, Glumes 1 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma 3 nerved, Lemma glabrous, Lemma apex acute or acuminate, Lemma distinctly awned, more than 2-3 mm, Lemma with 3 awns, Lemma awn 1-2 cm long, Lemma awned from tip, Lemma awn twisted, spirally coiled at base, like a corkscrew, Lemma awn once geniculate, bent once, Lemma margins inrolled, tightly covering palea and caryopsis, Lemma straight, Callus or base of lemma evidently hairy, Callus hairs shorter than lemma, Palea present, well developed, Palea membranous, hyaline, Palea shorter than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.
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Aristida basiramea

provided by wikipedia EN

Aristida basiramea, the forked three-awn, is a species of grass in the family Poaceae native to North America. The specific epithet basiramea means "branching from base".

Description

Aristida basiramea is an annual grass and freely branches from the base, reaching 2–6 dm (7.9–23.6 in) in height. The wiry culms are sparingly branched. The narrow leaves of the grass are flat and become involute towards their tip. The panicles are borne in the basal sheathes. The glabrous glumes at the base of the spikelets gradually taper to a point, averaging from 1–1.5 cm (0.39–0.59 in) in length. The glumes have a single vein and are unequal in length.[1] The lemma, excluding the awns, is approximately 1 cm (0.39 in) long. The delicate lateral awns are 5–10 mm (0.20–0.39 in) in length and can be erect or spreading. The middle awn is much longer and stouter, being 1–1.5 cm (0.39–0.59 in) long, and loosely spirals when dry.[2] The spikelets are light brown when mature. The seeds are chestnut brown and 6–7 mm (0.24–0.28 in) long.[3]

The grass flowers from August to October.[4]

Habitat and distribution

Aristida basiramea is endemic to North America, particularly the midwest, though outliers in distribution include as far south as Texas and as far east as Maine. The grass is rare in Canada, only found in southern Ontario and Quebec. The grass is not found any farther north than the upper peninsula of Michigan.

The species grows in weedy conditions such as roadsides or pastures and will often grow in pine barrens. In Canada the grass can be found occasionally in open and dry sand ridges or dunes. It prefers dry or sandy soil and warm climates, though it is the hardiest member of its genus.[1]

Ecology

Despite being a poor forage grass as well as being harmful to grazing animals due to its calli, Aristida basiramea is an important source of forage in springtime, especially in its western distribution. Small mammals and quail will eat the hardy seeds.[5]

Conservation

In Canada, Aristida basiramea is threatened by the decline and fragmentation of its sandy habitat. Prevention of fire in particular endangers the habitat of the species, as fire no longer maintains natural succession of the sand ridges. The greater competition arising from lack of wildfires in particular threatens the species. The glossy buckthorn, the spotted knapweed, and the white sweet clover are all invasive species which threaten the grass.[1]

References

  1. ^ a b c Gary Michael Allen (2003). COSEWIC Assessment and Status Report on the Forked Three-awned Grass Aristida basiramea in Canada (PDF). COSEWIC Secretariat. ISBN 0-662-34217-8.
  2. ^ Merrit Lyndon Fernald (1970). R. C. Rollins (ed.). Gray's Manual of Botany (Eighth (Centennial) - Illustrated ed.). D. Van Nostrand Company. p. 176. ISBN 0-442-22250-5.
  3. ^ "Aristida basiramea (Forked Three-awn)". Minnesota Wildflowers. 2018. Retrieved 3 August 2018.
  4. ^ Robert H. Mohlenbrock, Miriam Wysong Meyer (2001). Robert H. Mohlenbrock (ed.). Grasses: Panicum to Danthonia. The Illustrated Flora of Illinois. Vol. 1 (illustrated ed.). SIU Press. p. 334. ISBN 9780809323609.
  5. ^ K. W. Allred (2001). Draft of the Section on Aristida for the Flora of North America. p. 1-16.
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Aristida basiramea: Brief Summary

provided by wikipedia EN

Aristida basiramea, the forked three-awn, is a species of grass in the family Poaceae native to North America. The specific epithet basiramea means "branching from base".

license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN