Taxonomic name: Nassella tenuissima (Trin.) Barkworth
Synonyms: Stipa cirrosa E. Fourn., Stipa oreophila Speg., Stipa subulata E. Fourn., Stipa tenuissima Trin., Stipa tenuissima var. oreophila (Speg.) Speg., Stipa tenuissima var. planicola Speg.
Common names: angel's hair (Australia), elegant spear grass (Australia), fine-stemmed needle grass, Mexican feather grass, Mexican needle grass, pony tail (Australia), ponytail grass, Texas tussock, Texas tussock grass, white tussock
Organism type: grass
Nassella tenuissima )commonly known as Mexican feather grass) can be a weed in its native range at sites under high disturbance, such as that caused by overgrazing. It forms indigestible balls in the stomach of stock and, if they are forced to graze the infected pasture, they may lose weight and die, as Nassella tenuissima has a high fibre content and a low nutritive value. It is an extremely vigorous, invasive plant, which crowds out desirable pasture species, reducing stock carrying capacity. Nassella tenuissima can also crowd out native grasses in coastal or open areas. It is used for ornamental purposes and is available for sale in nurseries. In recent times, it has been promoted for 'its light and airy nature'.
Nassella tenuissima is a graceful, delicate and very fine textured ornamental grass. It grows in a dense fountain like clump with slender, wiry culms 0.3-0.6m tall. The leaves are 15.2-35.6cm long, 0.5mm wide, rolled inward very tightly so that they appear as thin wiry filaments (Christman, 2004). It blooms in late spring with a greenish flower cluster that persists well into fall as it ripens to golden brown (Christman, 2004). Flowers grow in unequal size; a single bisexual floret, which is longer than the floret; flower head, is often only partly exerted and spread from the end (DPI, 2004). Silvery inflorescence between summer to fall and becomes light straw coloured in fall (Evans, 2000). The main body of the seed is 2 to 3mm long DPI (2004). Young seedheads held among the leaves; mature seedhead to 25cm long; glumes to 1cm long; callus bearded (AWC, 2004).
agricultural areas, natural forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands
Nassella tenuissima grows on well drained soil and is very drought tolerant (Christman, 2004).
In Argentina Nassella tenuissima is being used as an ornamental and in some provinces like Tucumán it is used as thatch (F. Anderson, pers. obs.).
Species of a low nutritional value, with a high fibre content which animals do not consume; its abundance indicates degradation of the pasture (de Agrasar et al 2005).
Australian Quarantine in 1998 permitted the legal import of Nassella tenuissima despite all Nassella species are prohibited, because of a slip related to the species synonym. The importer used its old taxonomic name, Stipa tenuissima, in the import proposal, which was permitted.
Native range: Chile, Texas, New Mexico, Mexico, Argentina
Known introduced range: Australia, New Zealand, South Africa, other parts of the USA. It is known to have naturalised in California, New Zealand and South Africa. In 2004 N. tenuissima was found naturalised in northern New South Wales, Australia – a mere eight years between initial sale and naturalisation (McLaren et al 1999; Hosking 2004 in Glanznig, 2005a).
Introduction pathways to new locations
Nursery trade: Used as an ornamental and sold in nurseries (AWC, 2004).
Road vehicles (long distance): Seeds are also spread by machinery, in hay, water, mud and in the droppings of animals.
Local dispersal methods
For ornamental purposes (local): Used as an ornamental and sold in nurseries (AWC, 2004).
Translocation of machinery/equipment (local): Seeds are also spread by machinery, in hay, water, mud and in the droppings of animals.
The plant was introduced into Australia and marketed in nurseries under the names “elegant spear grass”, “pony tail” and ”angel's hair”. Education about its negative impacts and the destruction of existent plant specimens in gardens and nurseries could prevent this weed from becoming introduced into new countries or regions in the future.
Nassella tenuissima produces thousands of seeds, which are dispersed by wind, water or contaminated soil. Usually propagated from seed and often self sows (Evans, 2000; Christman, 2004).
In La Pampa, Argentina, Nassella tenuissima vegetates in autumn, flowers in November and sets seed in December-January (Freda Anderson., pers.comm., 2005).
Reviewed by: Freda Anderson, Centro de Recursos Naturales Renovables de la Zona Semiárida (CERZOS) -Universidad Nacional del Sur, Bahía Blanca, Argentina.
Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG) with support from the Terrestrial and Freshwater Biodiversity Information System (TFBIS) Programme (Copyright statement)
Last Modified: Thursday, 23 March 2006