Fimbristylis decipiens
Fimbristylis perpusilla
southern fimbry
Harper's fimbry
nearly distichous, mostly spreading, to 2/3 length of culms;
sheaths ciliate, sheath backs often pilose-hirsute;
ligule present, complete;
blades narrowly linear, 1.5–2.5 mm wide, flat or shallowly concave, margins scabrid, abaxial surface scattered-pilose, hirsute-ciliate at least proximally.
polystichous, spreading to ascending, mostly excurved, exceeding or exceeded by culms;
sheaths entire, backs glabrous;
ligule absent;
blades setaceous-filiform, to 0.5 mm wide, flat to involute, sparsely scabrid-ciliate.
anthelae simple or compound, open, divaricately branched, mostly as broad as long;
scapes slender, 1 mm wide, distally slightly compressed;
proximalmost involucral bract exceeding or shorter than anthela.
anthelae mostly simple, open, nearly as broad as long, ascending-branching, umbelliform, of 3–10 cormose spikelets;
scapes filiform, 0.5–0.6 mm thick;
proximalmost involucral bracts setaceous-bladed, exceeding anthela.
pale brown or red-brown, ovoid to lanceoloid, 5–6 mm;
fertile scales broadly ovate, 1.5–2 mm, acute- to obtuse-angled, midrib short-excurrent as mucro.
pale green to light brown, ovoid to globose or short-cylindric, 2–5 mm;
fertile scales lance-linear to oblong-linear, 1.5 mm, glabrous, midrib strongly excurrent, erect to excurved cusp.
stamens 1–2;
styles 2-fid, flat, fimbriate.
stamens 1;
styles 2-fid, slender, glabrous.
whitened-iridescent to brown, lenticular or pyriform-obovoid, 1 mm, cancellate, each face with 5–12 vertical rows of transversely oriented rectangular pits, achene margins distally papillose.
pale brown with iridescent tints, curved-cylindric, 0.4–0.6 mm, finely reticulate, in 12 vertical rows of narrowly rectangular, horizontal cells.
= 20.
= 10.
Fimbristylis decipiens
Fimbristylis perpusilla
In the Atlantic and Gulf Coastal plains, Fimbristylis decipiens often shares habitat with two close, likewise weedy, relatives: F. dichotoma and F. annua. From the former F. decipiens is distinguished by its annual habit, its papillose distal achene edges, and the more spreading anthela branches; from the latter it differs in its usually less papillose achene and its harder, more spreading foliage. No intergrades appear to occur among the three.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
The nearest relative of this ephemeral is Fimbristylis dipsacea, a similarly diminutive Eurasian and South American annual with broader, more spreadingcusped spikelets and oddly compound-papillate fruit.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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