Mexican feathergrass

Description

Nassella tenuissima is a species of grass known by the common names Mexican feathergrass, finestem needlegrass, fineleaved nassella, and Argentine needle-grass. It is native to the south-western United States, northern Mexico and Argentina. It is well-matched to climate in Australia and can be harmful to the Australian environment. It is sometimes used as an ornamental garden plant, but readily escapes, and has become naturalized in the San Francisco area. The availability of N. tenuissima via the internet and other plant purchasing situations makes its entry and naturalization in Australia almost inevitable. It is similar in appearance to Nassella trichotoma (serrated tussock) and has been recorded in Australia as a weed initially mistaken for that other invasive species. It is still widely referenced in botanical and horticultural literature under its synonym Stipa tenuissima, and has received the Royal Horticultural Society's Award of Garden Merit under that name. 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". It is usually considered segregate from the genus Stipa and includes many New World species formerly classified in that genus. As of 2011, The Jepson Manual includes Nassella within Stipa. 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.