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Vegetative Morphology

 
Plants usually perennial, rarely annual; cespitose, occasionally rhizomatous.
Culms 10-175(210) cm, sometimes branched at the upper nodes, branches flexible.
Prophylls not evident, shorter than the sheaths.
Leaves mostly basal, not overwintering.
Sheaths open; cleistogenes sometimes present.
Auricles absent.
Ligules membranous, sometimes pubescent or ciliate.
Blades of basal leaves 3-60 cm long, 0.2-8 mm wide, apices narrowly acute to acute, not sharp.
Blades of flag leaves 1-80 mm, bases about as wide as the top of the sheaths.

Reproductive Morphology

 
Inflorescences terminal panicles, sometimes partially included at maturity.
Spikelets 3-22 mm, with 1 floret.
Rachillas not prolonged beyond the base of the floret.
Disarticulation above the glumes, beneath the floret.
Glumes longer than the floret, narrowly lanceolate or ovate, basal portion usually purplish at anthesis, the color fading with age, (1)3-5-veined, sometimes awned.
Florets usually terete, sometimes slightly laterally compressed.
Calluses blunt or sharp, glabrous or antrorsely strigose.
Lemmas usually papillose or tuberculate, at least distally, sometimes smooth throughout, glabrous or variously hairy, strongly convolute, wrapping 1.2-1.5 times around the caryopses, apices not lobed, fused distally into crowns, these often evident by their pale color and constricted bases.
Crowns mostly glabrous, rims often bearing hairs with bulbous bases.
Awns terminal, centric or eccentric, deciduous or persistent, usually twice-geniculate, second geniculation often obscure.
Paleas up to 1/2 as long as the lemmas, glabrous, without veins, flat.
Lodicules 2 or 3, if 3, the third somewhat shorter than the other 2.
Anthers 1 or 3, if 3, often of 2 lengths, penicillate.
Ovaries glabrous.
Styles 2, bases free.
Caryopses glabrous, not ribbed.
Hila elongate.
Embryos to 2/5 as long as the caryopses.

Species Distribution Maps

Nassella neesiana Nassella leucotricha Nassella manicata Nassella lepida
Nassella pulchra Nassella cernua Nassella tenuissima Nassella trichotoma
Nassella chilensis Nassella viridula    

Chromosome Number(s)

x = 7, 8.

Additional Notes

Nassella used to be interpreted as a South American genus of approximately 14 species. It is now interpreted as including at least 116 species, the majority of which are South American. The additional species were previously included in Stipa. There are eight species in the Flora region, one of which is introduced; two additional species treated here were found in the region at one time, but have not become established. The strongly convolute lemmas distinguish Nassella from all other genera of Stipeae in the Americas and, in combination with the reduced, ecostate, glabrous paleas, from all other genera in the tribe worldwide.

Many species of Nassella develop both cleistogamous and chasmogamous florets in the terminal panicle. The cleistogamous florets have 1-3 anthers that are less than 1 mm long; the chasmogamous florets have 3 anthers that are significantly longer. In addition, some species develop panicles in the axils of their basal sheaths. Spikelets of cleistogenes have reduced or no glumes, and florets with no or very short awns.

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Name/Synonymy Publication Info

Nassella E. Desv. in Gay, Fl. chil. 6:263 (1854) [1853 on title page; printed March 1854]. LEC: Nassella pungens E. Desv. [Parodi, Darwiniana 7:14 (1947)].

Treatment from

M.E. Barkworth. Nassella in Flora of North America, volume 24. In prep. Oxford University Press.

Fact Sheet Developed By

Pedro Oñativia Lake © 2006.