58 GENERAL REMARKS ON THE 



species connecting them with each other, and Panicum with 

 Paspahmi. 



Panicea have their maximum within the tropics, and 

 they cease to exist in the most northern parts of Europe 

 and the higher soutliern latitudes. Of this tribe, 99 species 

 have been observed in Terra Austrahs, 79 of which were 

 found within the tropic, and of these, 66 only within it. 

 There is no Australian genus of this tribe, Neurachne and 

 Hcmarthria excepted, which is not chiefly intratropical. 



The second tribe, which may be called PoACEiE, is more 

 numerous than Paniceae, and comprehends the greater part 

 of the European . genera, as well as certain less extensive 

 genera peculiar to the equinoctial countries ; it extends also 

 to the highest latitudes in wdiich Phscnogamous plants have 

 been found, but its maximum appears to be in the tempe- 

 rate climates considerably beyond the tropics. The locusta 

 in this tribe may consist of one, of two, or of many flowers, 

 and the two-flowered genera are distinguished from Panicese 

 by the outer or lower flower being ahvays perfect ; the ten- 

 dency to imperfection in the locusta existing in opposite 

 directions in the two tribes. In conformity with this ten- 

 dency in Poacese, the outer valve of the perianthium in the 

 single-flowered- genera is placed within that of the gluma, 

 and in the many-flowered locusta the upper flowers are fre- 

 quently imperfect. There are, however, some exceptions 

 to this order of suppression, especially in iVruncIo Phrag- 

 niites, Campulosus, and some other genera, in Avhicli the 

 outer flower is also imperfect, but as all of these have more 

 than two flowers in their locusta, they are still readily dis- 

 tinguished from Panicese. 



In Terra Austrahs the Poacece amount to 115 species, 

 of which 69 were observed beyond the tropic and of these 

 63 only beyond it ; but of the 52 species that occur within 

 the tropics 49 belong to genera which are either entirely 

 or chiefly intratropical, and of the remaining three species, 

 two, namely Arundo Phragmites, and Agrostis virginica, 

 are very general and also aquatic plants. The distribution 

 of this tribe, therefore, in Terra Austrahs agrees with that 

 which obtains in other parts of the world, 



