keys to the vascular plants of east texas - Botanical Research ...

FIMBRISTYLIS Vahl FIMBRY
FIMBRISTYLIS/CYPERACEAE 607
Annuals or perennials, usually cespitose, sometimes rhizomatous; leaves basal, filiform to linear;
ligule of short hairs or absent; inflorescence a simple or compound, umbel-like cyme
(sometimes referred to as an anthela) at end of flowering culm (scape), of peduncled or sessile
spikelets, often subtended by a leafy involucre; scape usually longer than leaves; spikelets several–many-flowered;
scales of spikelets spirally imbricate; flowers perfect; perianth absent;
style base often dilated and fimbriate; stamens 1–3; achenes lenticular to biconvex, obovoid, or
trigonous, often minutely reticulate-honey-combed, without a tubercle.
AA genus of well over 100 to ca. 200 species, depending on circumscription, pantropical but
with significant numbers in warm temperate regions (Tucker 1987; Kral 2002b). Most species
grow in disturbed wet habitats (Kral 1971; Tucker 1987); some are used as copper indicators or
for their fiber. Abildgaardia, Bulbostylis, and Fimbristylis share anatomical features not reported
in any other Cyperaceae and are closely related. As a result, both Abildgaardia and
Bulbostylis have sometimes been included in Fimbristylis, but the genera are separated by a
number of characters (Kral 1971; Tucker 1987). Kral (1971) gave a detailed discussion of the relationships
of these genera and the difficulty of generic delimitation in the Cyperaceae. (Latin:
fimbria, a fringe, and Greek: stylos, pillar, column, or style, from the style being fringed with
hairs in some species)
REFERENCES: Svenson 1957; Gordon-Gray 1971; Kral 1971, 2002b; Godfrey & Wooten 1979;
Kolstad 1986a; Tucker 1987.
1. Styles 3-branched; achenes trigonous OR not so; spikelets usually 2–7 mm long; plants annual.
2. Spikelets lanceolate to linear-oblong, usually 3–7 mm long, apically acute; scales of spikelets
acute to acuminate; ligules of short hairs present; achenes trigonous, the surfaces not reticulate
or only faintly so, smooth or warty especially at base _____________________________ F. autumnalis
2. Spikelets usually ovoid to nearly round, 1.5–4 mm long, apically rounded; scales of spikelets
obtuse; ligules absent; achenes not trigonous or only obscurely so, obovoid, the surfaces reticulate
and usually warty _________________________________________________________ F. miliacea
1. Styles 2-branched; achenes lenticular to biconvex or obovoid; spikelets 3–15(–20) mm long; plants
annual or perennial.
3. Plants low growing annuals to only 15 cm tall; spikelets sessile, all close together in a capitate
cluster; leaf blades filiform, < 1 mm wide; achenes ca. 0.5–0.7 mm long _______________________ F. vahlii
3. Plants annuals or perennials usually more than 15 cm tall (to 1.5(–2) m tall); spikelets (at least
1 or more) peduncled; leaf blades narrowly linear to linear, 1–5(–rarely more) mm wide; achenes
0.8 mm or more long.
4. Plants perennials, with rhizomes (these usually either elongate and slender or short and
knotty) OR with hard bulbose bases OR with leaf bases hard, leathery, and dark brown;
ligules of short hairs present OR ligules absent or incomplete.
5. Long, slender, scaly rhizomes present (can be observed if plant is carefully removed
from the substrate); plant bases neither bulbose nor with hard, leathery, dark brown leaf
bases; scapes typically compressed; ligules of short hairs present __________________ F. caroliniana
5. Long, slender, scaly rhizomes absent; plant bases EITHER bulbose, hard and knotty, often
joined together into a short stoutish rhizome OR with leaf bases hard, leathery, and dark
brown OR (in F. puberula var. interior) with dense clusters of short, slender, twisted, pale
reddish-brown to orangish rhizomes; scapes not compressed or only slightly so; ligules
of short hairs present OR ligules absent or incomplete.
6. Plants densely cespitose, 80–150(–200) cm tall; bases of leaves hard, leathery, usually
dark brown; plant bases neither bulbose nor with short rhizomes; scapes 1.5–2(–3)
mm wide, ca. as wide as or wider than leaf blades ______________________________ F. castanea
6. Plants loosely cespitose in small tufts or with culms solitary, 15–60(–100) cm tall; bases
of leaves not as above; plant bases EITHER bulbose, hard and knotty, often joined