Family: Poaceae
Vanilla Sweetgrass
[Hierochloë annulata Petrov., moreHierochloe borealis (Schrad.) Roem. & Schult., Hierochloe odorata (L.) P.Beauv.] |
Kelly W. Allred and Mary E. Barkworth Plants perennial; loosely cespitose or the culms colitary; rhizomes elongate, 0.7–2 mm thick. Culms (5)15–50(90) cm tall. Sheaths brownish or reddish, glabrous or puberulent; ligules 0.5–6.5(8) mm long, truncate, obtuse, or acute; blades of basal and cauline leaves 10–30 cm long, 2–8 mm wide, usually flat, sometimes inrolled, abaxial surface glabrous or puberulent, without prominent cross venations, adaxial surface glabrous; flag leaf blades 0.3–1.5(4.5) cm long, 1.5–4.5(6) mm wide. Panicles (2)4–9(12.5) cm long, (1.5)2–5(7) cm wide, open, pyramidal, with 8–100 spikelets; branches with 3+ spikelets. Spikelets (2.5)3.–7.5 mm long, mostly tawny, sometimes tinged with green; rachilla internodes 0.15–0.3 mm long, glabrous. Glumes subsequal, exceeding the florets, glabrous; lowest glume in each spikelet with length 2–5 times its width, usually shorter and wider than the upper glume. Lowest 2 florets: staminate; lemmas hairy, particularly distally, hairs brown, often papillose-based, to 0.8 mm long on the margins and to 0.3 mm long near the tips, margins with 11–26 hairs per mm, midvein usually terminating at the tops or extending beyond as an awn, tips acute to rounded, entire or bifid, unawned, mucronate or with a thin awn up to 0.5 mm long; lowest lemma 3.4–5 mm long, 1–1.5 mm wide, length usually less than 4 times width; bisexual florets: lemmas 2.5–4 mm long, usually hairy distally, hairs 0.1–0.5 mm long, appressed or almost so at mautiry, longer, divergent hairs, if present, concentrated near the midvein; anthers of staminate florets 0.9–2.3 mm long, those of the bisexual floret 1.2–1.6 mm long. 2n = 28, 42. Anthoxanthum nitens [= Hierochloë odorata (L.) P. Beauv.] is primarily a European species. In North America, it grows along the eastern coast rom Labrador to New England, It is not known from Greenland although it grows in both Iceland and northwestern Europe. It is found in wet meadows and at the edges of sloughs, marshes, roadsides, and fields. Only A. nitens (Weber) Y. Schouten & Veldkamp subsp. nitens grows in North America; it is also present in Europe. It differs from A. nitens subsp. balticum (G. Weim.) G.C. Tucker in beings almost always awned and in being tetraploid with 2n = 28. North American taxonomists have generally treated A. hirtum and A. nitens as a single species, A. hirtum (or, more often, as Hierochloë odorata). The two are distinct, although not easy to distinguish. Weimarck (1973) separate d the two based on the density of the lateral hairs and development of the awns of the staminate florets. The distribution and length of hairs on the tips of the bisexual florets was found to be more reliable when preparing this account. M.J. Harvey (pers. comm.), who treated the two as a single species, noted that plants from the Maritime Provinces collected near salt water were uniformly 2n = 28 whereas those from the interior of New Brunswick and westward had 2n = 56. This observation is consistent with Weimark’s chromosome counts and distribution maps. |