|Gordon C. Tucker|
Plants perennial; cespitose. Culms 5-150
cm, erect. Sheaths open nearly to the base; auricles absent; ligules about
as long as wide, membranous, truncate to rounded, ciliate-erose; blades convolute
or involute, adaxial surfaces ribbed over the veins. Inflorescences narrow
panicles or racemes; disarticulation above the glumes and beneath
the florets. Spikelets laterally compressed, with (1)2-8 florets; rachillas pilose
on all sides, terminating in reduced florets. Glumes equaling
or exceeding the adjacent lemmas, exceeded by the distal florets, 1-3(5)-veined; calluses acute,
strigose; lemmas pilose or glabrous, 3-5-veined, apices acute,
toothed, awned from about midlength, awns geniculate, twisted and terete
below the bend; paleas shorter than the lemmas, wings more than
1/2 as wide as the intercostal region; lodicules 2, lobed; anthers 3; ovariespubescent
distally. Caryopses with a solid endosperm, longitudinally grooved,
with a terminal tuft of hairs; hila more than 1/2 as long as
the caryopses, linear. x = 7. Name from the Greek helictos,
twisted, and trichon, awn, referring to the lemma awn.
Helictotrichon has about 15 species. Most are native to Europe; one is endemic to the Flora region, and one has been introduced as an ornamental. The genus is sometimes interpreted as including Avenula.
Culms 5-20 cm tall; panicles 2-8 cm long, most branches with 1 spikelet; plants native ..... 1. H. mortonianum
Culms 30-150 cm tall; panicles 8-20 cm long, most branches with 3-10 spikelets; plants cultivated as ornamentals ..... 2. H. sempervirens
1. Helictotrichon mortonianum (Scribn.) Henrard
Culms 5-20 cm. Ligules 0.5-1 mm, truncate to rounded, ciliate; blades 3-6 cm long, 1-2 mm wide, involute or convolute, strigose, particularly on the adaxial surfaces. Panicles 2-5(8) cm; branches erect, usually with 1 spikelet each. Spikelets 8-12 mm, with (1)2(3) florets, distal florets unawned or awned. Glumes equal or nearly so, 8-11 mm, acuminate or awn-tipped, awns 0.3-0.5 mm; lowest lemmas 7-10 mm, 3-veined, apices 4-toothed, awns 10-16 mm; anthers 1.5-2 mm. 2n = 14, 28.
Helictotrichon mortonianum grows in alpine and subalpine meadows and summits at 3050-4110 m. It is restricted to the central and southern Rocky Mountains of the contiguous United States.
2. Helictotrichon sempervirens (Vill.) Pilg.
Culms 30-100(150) cm. Ligules 0.5-1.5 mm, truncate, ciliate; blades 15-60 cm long, 2-4 mm wide, usually convolute and 0.9-1.5 mm in diameter, glaucous, scabridulous, basal blades deciduous when dead. Panicles 8-20 cm; branches ascending, with 3-7(10) spikelets. Spikelets 10-14 mm, with 3(5) florets, distal florets unawned. Glumes subequal to unequal; lower glumes 7-10 mm; upper glumes 10-12 mm; lowest lemmas 7-12 mm, awns about 15 mm; anthers about 5 mm. 2n = 28, 42.
Helictotrichon sempervirens is a native of the southwestern Alps in Europe, where it grows on rocky soils and in stony pastures. In the Flora region, it is frequently grown as an ornamental species.