87 



the Transvaal, and often forms clans or societies. T . flavida 

 is a Transvaal High Veld species, and T. ramosa is a xero- 

 phytic suft'rutescent species from (iriqualand West. T. dregeana 

 belongs to the hydrosere in Natal, being found near streams. 

 It is also recorded for the Transvaal and the Shire Highlands. 

 All the species are tropical. 



Triraphis. This is chiefly a Western genus from Nama- 

 qualand, Hereroland and Amboland. T. elliotii, T . purpurea, 

 T. fleehii, T. nana, T. purpurea, T. ramosissima, T. schinzii 



are representative Western species of which one or two (T. 

 flechii, T. nana) extend eastward through the Kalahari to 

 Bechuanaland and Griqualand West. T. nana is a dwarf 

 annual, scarcely an inch high, and all the species are very 

 xerophytic. T. rehmanni has quite a different distribution, 

 from the Cape at Uitenhage through the Free State, Transvaal 

 and Natal. On the eastern side it is a Mountain Veld species 

 or it grows in open stony Veld. No records for Natal are 

 given in the Flora Capensis. 



Trisetum pumilum very rare in the South West, probably 

 introduced. 



Fio-. 21. — Transverse Section of a portion of a leaf of Tristachya leucothrix 



(x about 50). 



Tristachya. T. leucothrix is widely distributed over the 

 whole Eastern region, and forms definite societies in climax 

 grassland. T. rehmanni is common in the Transvaal High 

 Veld and T. biseriata is a Basutoland species. They are coarse 

 tufted grasses similar to the Andropogons. Fig. 21 shows a 

 transverse section of part of the leaf of T. leucothrix. The 

 ridges are practically obsolete, and there is little sclerenchyma. 

 The motor cells are on the surface, and not at the bottom of 

 grooves, but they cause the leaf to roll up. Panicum serratum 

 is similar. 



Urelytrum squarrosum. Fairly common in the High 

 Veld of Natal and the Transvaal. It resembles Trachypogon 

 polymorphic. The variety robusta is larger and stouter. 

 Fiff. 22 shows a cross section of the leaf. The ridges are 



