A Kkvision of tii K \Yi«>tkkn Ai strauan 
SlM'H II S OF TltfODl A R.Bit. 1 
2.— A REVISION OF THE W ESTERN AUST 11 A LI AN 
SPECIES OF TRIODIA R. BR. 
By Nancy T. Burbidce, B.Sc. (Hons.). 
Road, 14tli March, 1044. 
Voinmunioated by A. (Jakdner. 
The revision of the species of this genus in Western Australia was under- 
taken as a result of investigations concerning the management, and currying 
capacity of certain natural pastures in the north-west of the State. The 
investigations were being made by officers of the Institute of Agrieu/turo of 
the University of Western Australia. The species are all xerophytic grasses 
with a characteristic tussock habit and pungent pointed loaves. Although 
the genus is found throughout tropical and arid Aust ralia., it. is only in Western 
Australia that there is a definite pastoral zone dependent on these grasses. 
The zone, speaking very broadly, is a triangle with its base lino along the 
Ashburton River and its apex at Broome. To t he sout h of this area, the 
country grades into the mulga zone with Avne la spp. as the' dominant, forms. 
To the east is desert country whore more Triad ia occurs but, by reason of 
poor water supplies and general inaccessibility, no leases have been taken up. 
{South of this pastoral /one some species of Triodin do occur hut they are of no 
value to t he pastoral ist. 
The name c ‘ spinifox ” is commonly, but erroneously, attached to t hese 
grasses. The word is so widely and so consistently used by pastoralists t hat 
it is accepted in some places in this paper to avoid further confusion. Actually 
the name fipinifex belongs to another genus of grasses which, in this part of 
Australia is commonly found on sand dunes near the coast. Some of the 
species of Triodin have been called “porcupine grass” though not in this 
State and this name will not bo used in this paper. 
Economic) Value tn Western Australia. 
By far the most important species is Triodin pungem since it is the only 
one which is readily eaten by sheep. It. is also widely distributed throughout 
the more arid sections of the State which have a predominantly summer 
rainfall. It is a variable species and edibility is related to t he growth form, 
as well as to the age of the plant. 'This will he further discussed under the 
spec bos description. T. pungent is tolerant, of different soil conditions and it. 
ranges through the whole of the pastoral zone, described above, and extends 
right across to Queensland. As will ho shown it. has been collected, by the 
author, over a considerable area of the pastoral zone and field notes concern- 
ing variability am available. So far as edibility is concerned trials carried 
out at Warralong Station, < ’oongan River, by officers of the Institute of Agri- 
culture, showed that the digestibility of this species is approximately HO per 
cent. 
With reference to tho ecological association of which T. pungent* is t he 
dominant species it should be realised that herbage resulting from t he growth 
of annual fodder plants is scanty in most seasons, in comparison with the 
flush of growth which appears in mulga country. Tho perennial grasses 
form a closed community and, except whore they are burnt hack, there is 
little ephemeral growth. The practice of burning back the tussocks when 
h 8000/45 
