Tristachya leucothrix Nees

Gramineae

 
Author: D. B. Hoare
Synonyms

Apochaete hispida (L.f.) J.B.Phipps, Tristachya hispida (L.f.) K.Schum.

Common names

Rooisaadgras, Trident grass, Hairy trident grass.

  Taxonomy

Panicoideae; Panicodae, Arundinelleae.

  Origin and geographic distribution

There are about 20 species of Tristachya from tropical America, Madagascar and tropical and southern Africa of which 6 species are indigenous to southern Africa. Tristachya leucothrix occurs in tropical to southern Africa. In South Africa it is found in the Fynbos, Savanna and Grassland Biomes.

  Description

A relatively densely tufted perennial grass with unbranched culms that grows to a height of 150-900 mm tall. The leaves are concentrated at the base, are hairy and become curled when dry and the basal leaf sheaths are covered with dense brown hairs. The leaf blades are 300-400 mm long and 2 mm wide. The ligule is a fringe of hairs. Plants with hermaphrodite florets. The inflorescence is a single open or contracted raceme. The spikelet-bearing axis is persistent. The spikelets are in triplets, 24-45 mm long, disarticulating above the glumes. Pedicels are connate, the glumes and lower lemma have many tubercle-based hairs. Glumes are more or less equal, awnless. The female fertile lemma has side awns 3-5 mm long and central awns 50-100 mm long.
Tristachya leucothrix is closely related to T. biseriata and T. rehmannii. The latter species have either only two rows of hairs on the glumes (T. biseriata) or are entirely hairless (T. rehmannii).

  Use

A relatively good natural grazing species that is particularly attractive to sheep. It has moderate leaf production, but becomes hard and unpalatable later in the season so is usually only grazed earlier on.

  Cytology

Chromosome base number, x = 10 and 12.

  Leaf blade anatomy

C4 photosynthetic pathway.

  Toxicity

None reported and considered to be non-toxic.

  Ecology

Occurs in the temperate cooler, wetter, high altitude parts of southern Africa. Rainfall may occur at any time of the year, but is concentrated in summer, and may be from 700-1200 mm per annum. Usually grows in marshy grassland on mountain slopes and hillsides, where it may be locally dominant. It is a climax species that increases in under-utilized rangeland that is burned regularly.

  Soil requirements

Usually found in sandy soil.

  Propagation and planting

T. leucothrix is not propagated.

  Growth and development

Broadly summer-to late summer growing species that flowers from October to March.

  Diseases and pests

None known.

  Performance

Moderate to slow-growing.

  Links
  References

Acocks, J.P.H. 1988. Veld types of South Africa (3rd edn.). Mem. Bot. Surv. S. Afr. No 28. Government printer, Pretoria.

Gibbs-Russell, G.E., Watson, L., Koekemoer, M., Smook, L. Barker, N.P., Anderson, H.M., Dallwitz, M.J. 1991. Grasses of southern Africa. Memoirs of the Botanical Survey of South Africa, No. 58, National Botanical Institute, Pretoria.

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