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fiberoptic grass, low bulrush, low clubrush, low lateral clubrush, tuft clubrush

Gulf Coast bulrush

Habit Plants annual (or perennial?); rhizomes usually obscured by culm bases and very short, sometimes vertical and elongated. Plants annual; rhizomes absent.
Culms

4–40 cm × 0.2–0.5 mm.

2–20 cm × 0.2–0.3 mm.

Leaves

sometimes sparsely orange-punctate at 10–15X;

sheaths usually reddish proximally;

distal blade rudimentary to much longer than sheath, often exceeding culm, to 20 cm × 0.2–1 mm.

sheaths green to stramineous;

distal blade mostly much longer than sheath, to 3 cm × 0.2 mm.

Inflorescences

involucral bract 1, sometimes subtending flower or resembling enlarged floral scale, 2–6(–23) mm.

involucral bract 1, 3–10(–25) mm, rarely a second bract to 5 mm.

Spikelets

2–5 × 1–2 mm;

scales partly or completely dark orange to red-brown, rarely stramineous, midrib greenish to stramineous, not gibbous, obscurely to prominently 3–11-veined, midrib keeled near apex, membranous, hyaline, apex rounded to acute, with mucro less than 0.1 mm;

proximal scale to 2 mm;

other scales 1.2–1.8 × 1–1.3 mm.

2–8 × 1–1.5 mm;

scales colorless, stramineous, or pale greenish, markedly gibbous, veinless or obscurely 3–7-veined, midrib keeled, finely reticulate at 40X, membranous, hyaline, apex rounded, mucronate, or awned;

proximal scale to 1.5(–5) mm, awn to 3 mm;

other scales 1–1.2 mm, apex, mucro 0.1 mm.

Flowers

anthers 0.3–0.6 mm;

styles 3-fid or 3-fid and 2-fid.

anthers 0.2 mm;

styles 3-fid.

Achenes

falling separately from scales, medium to dark brown or stramineous, ellipsoid to obovoid, compressed-trigonous to thickly biconvex, lateral angles usually prominent, abaxial angle prominent to obscure, faces convex or adaxial face slightly concave, 0.8–1 × 0.5–0.7 mm, distinctly papillose at 10–15X to obscurely papillose at 40X, often with thin whitish surface layer.

often falling with and clasped by floral scales, whitish (or orange-brown when unripe), broadly ellipsoid to obovoid or outline subcircular, nearly equilaterally trigonous, faces convex, 0.7–0.9 × 0.5–0.6 mm, minutely papillose at 40X, papillae in many vertical rows or usually obscured by thick whitish surface layer.

2n

= 30.

Isolepis cernua

Isolepis pseudosetacea

Phenology Fruiting late spring–winter (Pacific Coast), winter–spring (Texas). Fruiting spring–summer.
Habitat Wet, freshwater to brackish places on beaches, dunes, marine bluffs, sandy areas, mostly coastal Wet, freshwater, often drying, places in grasslands, open woods, limestone barrens, cultivated fields, waste places
Elevation 0–800 m (0–2600 ft) 0(–100) m (0(–300) ft)
Distribution
from FNA
CA; OR; TX; WA; BC; Mexico (Baja California); temperate South America; Eurasia; Africa; Australia; New Zealand
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; GA; LA; MO; MS; TX; s Europe; n Africa
[BONAP county map]
Discussion

Isolepis cernua is widespread and variable. Four varieties were recognized by A. M. Muasya and D. M. Simpson (2002). Only var. ceruna is known from North America. The earliest collection I have seen from the Pacific Coast is from 1888; the earliest collection I have seen from Texas is from 1974.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Isolepis pseudosetacea is often mistaken for the very similar I. carinata, with which it sometimes grows but does not intergrade. It may easily be distinguished by the characters given in the key.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23, p. 139. FNA vol. 23, p. 138.
Parent taxa Cyperaceae > Isolepis Cyperaceae > Isolepis
Sibling taxa
I. carinata, I. pseudosetacea, I. setacea
I. carinata, I. cernua, I. setacea
Synonyms Scirpus cernuus, Scirpus cernuus var. californicus, Scirpus cernuus subsp. californicus Scirpus pseudosetaceus, I. molesta, Scirpus molestus
Name authority (Vahl) Roemer & Schultes: in J. J. Roemer et al., Syst. Veg. 2: 106. (1817) (Daveau) Gandoger: Cat. Pl. Espagne, 331. (1917)
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