Nassella

{{Short description|Genus of flowering plants}}

{{Automatic taxobox

|image = Nassella tenuissima.jpg

|image_caption = Nassella tenuissima

|display_parents = 3

|taxon = Nassella

|authority = (Trin.) É.Desv. (1854)

|type_species = Nassella pungens

|type_species_authority = É.Desv.

|subdivision_ranks = Species

|subdivision = Many, see text

}}

Nassella, or needlegrass, is a New World genus of over 100 perennial bunchgrasses found from North America through South America. The Latin word nassa refers to "a basket with a narrow neck".[http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?8738,9138 Nassella.] The Jepson Manual. It is usually considered segregate from the genus Stipa and includes many New World species formerly classified in that genus.Barkworth, M. E. [http://herbarium.usu.edu/stipeae/nassella.htm Nassella E.Desv.] {{Webarchive|url=https://web.archive.org/web/20061205012508/http://herbarium.usu.edu/stipeae/nassella.htm |date=2006-12-05 }} Stipeae Pages. Intermountain Herbarium, Utah State University. June 13, 2003. As of 2011, The Jepson Manual includes Nassella within Stipa.[http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=45644 Stipa pulchra.] The Jepson Manual.

Nasella is characterized by strongly overlapping lemma margins and reduced, veinless paleae. The lemma tips are fused into the "crown", a short membrane that surrounds the base of the lemma. The rim of the crown usually has hairs.

Many species form both cross-pollinating and self-pollinating florets in the terminal panicle. The self-pollinating florets have 1–3 small anthers; the cross-pollinating florets have 3 longer anthers. Some species have self-pollinating inflorescences hidden in their basal leaf sheaths. These hidden inflorescences lack glumes and usually lack awns.

Some species (especially Nassella neesiana and Nassella tenuissima) are considered invasive pests, as the grass is not properly digested by ruminants.{{cite web | url=http://www.iucngisd.org/gisd/species.php?sc=458 | title=GISD }}{{cite web | url=http://www.iucngisd.org/gisd/species.php?sc=463 | title=GISD }}{{cite journal |url=https://www.researchgate.net/publication/225109211 |via=ResearchGate|doi=10.1007/s10530-010-9905-6 |title=The potential global distribution of the invasive weed Nassella neesiana under current and future climates |year=2012 |last1=Bourdôt |first1=Graeme W. |last2=Lamoureaux |first2=Shona L. |last3=Watt |first3=Michael S. |last4=Manning |first4=Lucy K. |last5=Kriticos |first5=Darren J. |journal=Biological Invasions |volume=14 |issue=8 |pages=1545–1556 |bibcode=2012BiInv..14.1545B |s2cid=14852104 }}