The grass family (Poaceae) is one of the largest flowering plant families, and also one of the most useful, containing numerous familiar economic crops. Many members of the family also offer horticultural value. The genus Nassella (syn. Stipa) contains over 100 species from warm and tropical regions of the southern hemisphere. N. tenuissima, or Mexican feathergrass, is a native of Mexico and Argentina, where it grows in open, rocky situations. It produces clumps of slender foliage, to 60cm in height, and the arching panicles of spikelets give it a wispy appearance. N. tenuissima is valuable in providing texture and movement to a planting in a well-drained, sunny position. Although perennial it can be treated as an annual, and will seed freely given suitable conditions.