100 



MISCELLANEOUS PUBLICATION 1271, U.S. DEPARTMENT OF AGRICULTURE 



Perennial grass - annual legume pastures t ■ ■ ' . J Volunteer burr medics &>^ 

 Annual grass- subterranean clover . '-'..-) Townsville stylo posture r%%$ 



Annual grass-annual medic postures S$S^i Rainfall (mm) 7»* 



Figuke 1. — Principal areas in which introduced annuals of value in animal production are sown or naturalized in 



Australia. (After Moore, 25.) 



Other common associates of annual medicagos 

 are silver grasses (Vulpia bromoides (L.) S. F. 

 Gray or V. myuros L.), saffron thistle (Cartha- 

 mus lanatus L.) or capeweed (Arctotheca calen- 

 dula (L.) Levyns), and the native Erodium cyg- 

 norum Nees. The ecology of Mediterranean an- 

 nual pastures is discussed by Rossiter (36). 



Townsville stylo (Stylosanthes humilis H. B. 

 K.) is the only introduced annual of any conse- 

 quence at present in tropical pastures, although 

 bulrush millet (Pennisetum typhoides (Burm.) 

 Staff and C. E. Hubbard) in the Northern Ter- 

 ritory, and phasy bean (Phaseolus lathyroides 

 L.) and a few other annual legumes are sown to 

 some extent in subtropical pastures. Townsville 

 stylo is adapted to a wide range of soils in areas 

 receiving more than C>5() mm. rain annually (see 

 figure 1). 



Native annual Sorghum spp. are common and 

 frequently dominant in the herbaceous layers of 

 30 million/ha. of tropical woodlands in the 

 Northern Territory and north of Western Aus- 

 tralia. These annuals flower and produce seed 

 early in the season and are of low nutritive value 

 in late summer. However. Robinson and Sageman 

 (33) have drawn attention to the value of Sor- 

 ghtwi australiense Garber and Snyder in provid- 

 ing feed early in the wet season before perennials 

 have resprouted in northwestern Australia. 



In arid shrublands, the common species of 

 ephemeral communities are Dactyloctenium radu- 

 lans (R. Br.) Beauv., Brachyachne convergem 

 (F. Muell.) Staff, Tragus australianus S. T. 

 Blake, Aristida contorta F. Muell., Enneapogon 

 polyphylhis (Domin.) N. T. Burbridge. Chloris 

 truncata R. Br., Tripogon loliiformis (F. Muell.) 



