Gramineae

Hyparrhenia aucta (Stapf) Stapf ex Stent
Hyparrhenia pilosissima (Hack.) J.G. Anders.

Hairy blue thatching grass, silky thatching grass

Panicoideae; Andropogonodae. There are about 55 species of which 20 are indigenous to southern Africa.

Occurs from eastern to southern Africa in savanna and grassland areas. It occurs on stony hillsides, stream-sides and in dry soils around seasonal wetlands. Sometimes dominant on the sides of roads where extra run-off water collects.

A robust perennial rhizomatous and tufted grass that grows to a height of 1500-2000 mm tall. Leaf blades are up to 600 mm long and 3-8 mm wide. The ligule is an unfringed membrane. Inflorescence is a leafy panicle with capillary branchlets and a complex of partial inflorescences and intervening foliar organs. The spikelets are sessile 4-5 mm long and densely hairy. Raceme pairs have 10-25 awns that are 8-20 mm long. The raceme bases are subequal, flattened and short-appendaged. The pedicellate spikelets are villous to hispidulous, rarely glabrous. H. dregeana is related to H. collina, H. tamba and H. rudis, from which it can be distinguished by its densely tufted habit and very many short awns.

This species is considered to be too hard and unpalatable to be used as a grazing grass, but is sometimes used as a thatching grass.

Chromosome base number, x = 10

C4 photosynthetic pathway.

Non reported and considered to be non-toxic.

Occurs in summer rainfall areas where the annual rainfall exceeds 500 mm per annum. Responds favourably to burning and will quickly become established as the dominant species where regular fires occur in the habitats which it prefers. In some parts of South Africa it is known to be dominant in wetlands that are usually dominated by Phragmites australis when these become dried out, and especially following fire during dry periods.

It grows in areas where there is more water than in surrounding areas, usually associated with water-logging, seasonal wetlands and along the margins of roads where runoff water collects.

H. dregeana is not propagated.

A summer-growing species that flowers anytime from November to May.

None known

Fast growing and quickly becomes dominant in habitats which it prefers.

Gibbs-Russell, G.E., Watson, L., Koekemoer, M., Smook, L. Barker, N.P., Anderson, H.M., Dallwitz, M.J. 1989. Grasses of southern Africa. Memoirs of the Botanical Survey of South Africa, No. 58, National Botanical Institute, Pretoria.

Gibbs-Russell, G.E., 1986. Significance of different centres of diversity in subfamilies of Poaceae in southern Africa. In: E.M.Van Zinderen Bakker, J.A.Coetzee & L.Scott (eds.) Palaeoecology of Africa and the surrounding islands. Vol. 17. pp. 183-191. A.A.Balkema, Rotterdam.

Van Wyk, E. & Van Oudtshoorn, F. 1999. Guide to grasses of southern Africa. Briza Publications, Arcadia, South Africa.