Flora of North America species comparison

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Trichophorum

bulrush, club-rush, deergrass, trichophore
Habit Herbs, perennial, cespitose, rhizomatous or not.
Culms

trigonous or terete.
Leaves

basal or subbasal;

sheaths bladeless or distal sheaths with blade to 5 mm, not fibrous;

ligules present;

blades obsolete or elongate, linear, less than 1 cm × 1 mm.
Inflorescences

terminal;

spikelets 1;

involucral bracts 1, suberect, scalelike, apex mucronate or awned.
Spikelets

scales 3–9, spirally arranged, each subtending flower.
Flowers

bisexual;

perianth of 0–6 bristles, straight, shorter than to about 20 times as long as achene, smooth or scabrous;

stamens 3;

styles linear, 3-fid, base persistent.
Achenes

trigonous or plano-convex.

Trichophorum
Distribution
from USDA
North America; Circumpolar to circumboreal; Andean and tropical Southeast Asian mountains
[BONAP county map]
Discussion

Species 9 (6 in the flora).

The appropriate name and typification for this genus have been debated widely. Arguments for conservation of Trichophorum Persoon in the sense used here, with the conserved type, T. alpinum (Linnaeus) Persoon, were presented (M. Salmenkallio and I. Kukkonen 1989), and the proposal was accepted in the Code. The proposal to segregate T. alpinum from the rest of Trichophorum, in the genus Eriophorella (J. Holub 1984), is based on characters that do not justify generic rank. In fact, K. Tan (1985) found that T. pumilum (Vahl) Schinz & Thellung could not be considered generically distinct from T. alpinum and created a combination for it within Eriophorella. The name Baeothryon Ehrhart ex A. Dietrich, previously considered to be a synonym of Trichophorum, has been shown to apply to a section of Eleocharis R. Brown (M. Salmenkallio and I. Kukkonen 1989; M. S. González-Elizondo and P. M. Peterson 1997).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Culms terete, smooth.
→ 2
1. Culms trigonous, angles scabrous.
→ 4
2. Achenes sharply trigonous; bracts 3.5–7.7 mm, exceeding spikes, apex with awn usually 1 mm or more.
T. clementis
2. Achenes compressed trigonous to plano-convex; bracts 1.6–4.5 mm, equaling or shorter than spikes, apex mucronate or awn less than 1 mm.
→ 3
3. Plants loosely cespitose, long-rhizomatous, slender; bracts to 2.5 mm, apex mucronate; perianth bristles absent; anthers 0.8–1.5 mm.
T. pumilum
3. Plants densely cespitose, not rhizomatous; bracts more than 3 mm, apex awned; perianth bristles 6; anthers 1.5–2.6 mm.
T. cespitosum
4. Flowers usually 15 or more per spike; perianth bristles white, flattened, to 20 times longer than achenes, smooth.
T. alpinum
4. Flowers fewer than 10 per spike; perianth bristles white to brown, terete, equaling or shorter than achenes, scabrous.
→ 5
5. Scales with obtuse apex, midribs not reaching apices in distal scales; leaves equaling or shorter than culms, 0.5–0.8(–1) mm wide.
T. clintonii
5. Scales (most or all) with mucronate apex, midribs excurrent; leaves equaling or exceeding culms, 0.8–2 mm wide.
T. planifolium
Source FNA vol. 23, p. 28. Author: William J. Crins.
Parent taxa Cyperaceae
Subordinate taxa
T. alpinum, T. cespitosum, T. clementis, T. clintonii, T. planifolium, T. pumilum
Synonyms Eriophorella
Name authority Persoon: Syn. Pl. 1: 69. (1805)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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