|Lisa A. Standley|
Plants usually perennial, rarely annual; cespitose
or rhizomatous, rarely both cespitose and rhizomatous. Culms (8)20-200
cm, glabrous or pubescent; nodes glabrous or retrorsely pubescent. Sheaths open; auricles absent; ligules 1-5
mm, membranous, entire or erose-ciliate, glabrous or puberulent; blades flat,
pubescent. Inflorescences terminal panicles, contracted to open. Spikelets laterally
compressed, with 2(3) florets, lower florets bisexual, upper floret(s)
staminate or sterile; rachillas curved below the lowest florets,
sometimes prolonged beyond the uppermost florets; disarticulation below
the glumes. Glumes equaling to exceeding the florets, strongly
keeled; lower glumes 1-veined; upper glumes 3-veined; calluses glabrous
or pubescent; lemmas firm, shining, glabrous or pubescent, obscurely
3-5-veined, often bidentate; lower lemmas unawned; upper
lemmas awned from below the apices, awns hooked or geniculate; paleas thin,
subequal to the lemmas; lodicules 2, glabrous, toothed or not
toothed; anthers 3; ovaries glabrous. Caryopses glabrous. x =
4, 7. Name from the Greek holkos, a kind of grain, perhaps sorghum.
Holcus, a genus of eight species, is native to Europe, North Africa, and the Middle East. One species, Holcus lanatus, has become widely naturalized in the Americas, Japan, and Hawaii; a second, Holcus mollis, has become a troublesome weed in some areas of the Flora region.
Awns 1-2 mm long, forming a curved hook at maturity; culms densely soft-pubescent adjacent to the lower nodes; plants cespitose, without rhizomes ..... 1. H. lanatus
Awns 3-5 mm long, straight or geniculate at maturity; culms glabrous or sparsely pubescent adjacent to the lower nodes; plants not cespitose, rhizomatous ..... 2. H. mollis
2. Holcus mollis L.
Creeping Velvetgrass, Houlque Molle
Plants perennial; not cespitose, rhizomatous, rhizomes to 40 cm. Culms 20-100(150) cm, usually decumbent at the base; lower internodes glabrous or sparsely pubescent. Sheaths glabrous or hirsute; ligules 1-5 mm, obtuse, erose; blades 2-20 cm long, 3-10 mm wide, pubescent. Panicles 4-20(22) cm long, to 3 cm wide; branches puberulent or ciliate; pedicels to 5 mm long, pilose, hairs to 0.3 mm. Spikelets 4-6(7) mm; rachillas hairy. Glumes exceeding and enclosing the florets, subequal, nearly the same width, ovate, membranous, whitish-green when young, straw-colored with age, veins ciliate, often purple, intercostal regions scabrous or glabrous, apices acuminate or acute, unawned; calluses densely to sparsely hirsute; lemmas 2-2.5 mm, glabrous, acute; upper lemmas bifid, awned above midlength, awns 3-5 mm, scabrous, straight or geniculate at maturity; anthers about 2 mm. 2n = 28 (35, 42, 49).
Holcus mollis grows in moist soil and disturbed sites, including lawns and damp pastures. It is a European introduction that has persisted in the Flora region, becoming a problematic weed in ungrazed pastures, prairie remnants, and oak savannahs in portions of the Pacific Northwest. It is also sold as an ornamental. There are two subspecies: Holcus mollis L. subsp. mollis (stems not thickened and tuberous at the base; panicles lax, brownish or purplish) and H. mollis subsp. reuteri (Boiss.) Malag. (stems thickened and tuberous at the base; panicles narrow, whitish). North American introductions belong to subsp. mollis.