Coefficient of Conservatism:
Coefficient of Wetness:
R. W. Smith
Sandy, marly, or peaty hollows and shores, especially where water levels have lowered; often abundant in a distinct zone. Very local northward.
Fimbristylis autumnalis is highly variable in size and whether erect or more or less prostrate, likely relating to how early in the season plants were able to germinate on the drawdown shores. Minute plants with just one spikelet can occur, and plants can rarely be up to 50 cm tall, with diffusely branched inflorescences. Some smaller plants may have all spikelets essentially sessile in the inflorescence.
Bulbostylis capillaris is superficially similar, but differs in its hair-like leaves, minute brown tubercle at the summit of the achene, and puberulent rounded scales. Fimbristylis autumnalis has flat leaves, lacks a persistent tubercle, and has glabrous acute to mucronate scales. Rhynchospora scirpoides is also similar, but differs from both in its 2-sided achenes with long persistent style, the base of which nearly or quite covers the summit of the achene, and its larger anthers (0.6–0.9 mm). The spikelets are generally thicker and darker, a useful impression for field recognition. Bulbostylis usually does not occur on the moist shores where F. autumnalis and Rhynchospora scirpoides are often growing together.