Deschampsia cespitosa
Deschampsia cespitosa subsp. cespitosa
tuft hair grass
deschampsie cespiteuse, tuft hairgrass
(7) 35-150 cm, erect, not rooting at the lower nodes.
(7)35-150 cm.
mostly basal, sometimes forming a dense 10-35 cm tuft;
sheaths glabrous;
ligules 2-13 mm, scarious, decurrent, obtuse to acute;
blades 5-30 cm long, usually at least some flat and 1-4 mm wide, the remainder folded or rolled and 0.5-1 mm in diameter, adaxial surfaces with 5-11 prominent ribs, ribs usually all papillose, scabridulous, or scabrous, sometimes puberulent, outer ribs sometimes more strongly so than the inner ribs.
8-30(40) cm, 4-30 cm wide, usually open and pyramidal, sometimes contracted and ovate;
branches straight to slightly flexuous, usually strongly divergent, sometimes strongly ascending, lower branches often scabridulous or scabrous, particularly distally, with not or only moderately imbricate spikelets.
8-30 cm long, 4-30 cm wide, open, nodding, pyramidal;
branches, both primary and secondary, usually divergent, usually sparsely to moderately scabridulous or scabrous, sometimes smooth.
2.5-7.6 mm, ovate to V-shaped, laterally compressed, usually bisexual, sometimes viviparous, bisexual spikelets usually with 2(3) florets, rarely with 1.
2.5-7 mm, not to slightly imbricate.
lanceolate, acute;
lower glumes 2.7-7 mm, entire, 1-3-veined, midvein sometimes scabridulous, at least distally;
upper glumes 2-7.5 mm, 1-3-veined, lanceolate, midvein smooth or wholly or partly scabridulous;
callus hairs 0.2-2.3 mm;
lemmas 2-5(7) mm, smooth, shiny, glabrous, usually purple over less than 1/2 their surface, purple or green proximally, if green, often with a purple band about midlength, usually green or pale distally, usually awned, awns (0.5)1-8 mm, attached from near the base to about midlength, straight or geniculate, sometimes exceeding the glumes;
anthers 1.5-3 mm.
subequal to the distal floret, lengths often less than 5 times widths;
lower glumes 2.5-5 mm, midveins smooth or scabridulous distally;
upper glumes 2-6 mm;
lemmas 2-4 mm, purple and/or green proximally, green to gold distally, the purple portion usually less than 1/2 the surface area, awns 1-8 mm, usually attached near the base, sometimes attached near midlength, straight or geniculate, exceeded by or exceeding the distal floret;
anthers 1.5-2 mm.
0.5-1 mm.
voucher specimens for these counts have not been examined.
2-8 mm;
blades 5-25 cm long, 1.5-3.5 mm wide when flat.
= 18, 24, 25, 26-28, about 39, 52.
Deschampsia cespitosa
Deschampsia cespitosa subsp. cespitosa
Deschampsia cespitosa is circumboreal in the Northern Hemisphere, and also grows in New Zealand and Australia. It is an attractive taxon that grows in wet meadows and bogs, and along streams and lakes, from sea level to over 3000 m in cool-temperate, but not arctic, habitats.
There are widely varying opinions concerning the taxonomic treatment of Deschampsia cespitosa. Tsvelev, Aiken, Murray, and Elven (per Murray, pers. com. 2005) recommend a narrow circumscription, and consider D. cespitosa to be introduced and mostly ruderal in regions other than Europe and western Siberia. Chiapella and Probatova (2003) adopted a much broader interpretation of D. cespitosa, treating many of the species recognized in, for example, Tsvelev (1995) as subspecies. There have been no interdisplinary, global studies of the complex. The circumscription adopted here is narrower than has been customary in North America. Some of the distribution records shown, particularly those from the northern part of the region, may reflect the broad interpretation of the species.
Lawrence (1945) demonstrated that, in western North America, Deschampsia cespitosa exhibits both ecotypic differentiation and a high degree of plasticity. The following three subspecies intergrade.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Deschampsia cespitosa subsp. cespitosa is treated here as a circumboreal taxon that is most prevalent in boreal and temperate North America, growing at 0-3000 m; many reports from arctic and alpine North America refer to what are treated here as D. sukatschewii or D. brevifolia. Even with this narrower interpretation, D. cespitosa is highly polymorphic. Plants with long awns are more prevalent in western North America but, within that region, do not appear to show any geographic or ecological preference (Lawrence 1945). Larger plants are difficult to distinguish from D. cespitosa subsp. beringensis. The morphological, geographic, and ecological boundaries between D. cespitosa subsp. cespitosa and subsp. beringensis need further study.
Many cultivars of Deschampsia cespitosa subsp. cespitosa have been developed. At one time, the most frequently cultivated plants were distinguished by their combination of large (20-40 cm) panicles and small (2.5-4 mm) spikelets, and were called D. cespitosa var. parviflora (Thuill.) Coss. & Germ, or D. cespitosa subsp. parviflora (Thuill.) K. Richt. Such plants are treated here as one part of the spectrum of variation in subsp. cespitosa.
The name Deschampsia cespitosa var. glauca (Hartm.) Lindm. has been applied in eastern North America to glaucous plants less than 75 cm tall, with spikelets only 3-4.5 mm long. Unfortunately, the name is illegitimate; there is no legitimate name available for such plants.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Panicles contracted at anthesis, the branches appressed to ascending; glumes 4.5-5.8 mm long, midvein of the lower glumes scabrous distally | subsp. holciformis |
1. Panicles open at anthesis, the branches strongly divergent to drooping; glumes 2-7.5 mm long; midvein of the lower glumes smooth or scabridulous distally. | → 2 |
2. Plants often glaucous; glumes 4.4-7.5 mm long; awns usually exceeding the lemmas; plants of the northwest coast of North America | subsp. beringensis |
2. Plants not glaucous; glumes 2-6 mm long; awns exceeded by or exceeding the lemmas; plants widespread in North America | subsp. cespitosa |
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