2G4 MORPHOLOGY OF ANGIOSPERMS 



Glumales. — The -world-wide distribution of this great 

 alliance, from tropical to boreal conditions, has resulted in no 

 continental tribes, comparatively few continental genera, and 

 very numerous cosmopolitan species. So far as geographic dis- 

 tribution is concerned, it may well represent the primitive 

 stock from which the following alliances have branched. 



Farixales. — This alliance is made up of a remarkable group 

 of isolated families, apparently being poorly adapted for cos- 

 mopolitan distribution. Only three of the eleven families have 

 a more extensive distribution than a hemisphere, Eriocaula- 

 ceae, the most cosmopolitan family, being massed in the tropics, 

 Commelinaceae occurring everywhere except in boreal condi- 

 tions, and Pontederiaceae being represented in all warmer re- 

 gions. Four families (Flagellariaceae, Restionaceae, Centro- 

 lepidaceae, and Eapateaceae) belong to the southern hemi- 

 sphere, three ( Mayacaceae, Xyridaceae, and Bromeliaceae) are 

 restricted to the western hemisphere, and Philydraceae are 

 Australian. 



Lieiai/es. — This series, in contrast to the Farinales, is made 

 up of characteristically cosmopolitan families. Liliaceae and 

 Iridaceae are literally cosmopolitan, Amaryllidaeeae and Tac- 

 caceae are massed in all tropical regions, Juncaceae are best de- 

 veloped in the cool temperates of the northern and southern 

 hemispheres, Haemodoraceae are represented in tropical Amer- 

 ica and Australia, Stemonaeeae are scattered in patches in 

 Australia, Asia, and Xorth America, and Dioscoreaceae are 

 mainly tropical. Only Velloziaceae are restricted to a single 

 hemisphere, and the restriction is remarkable, since all of the 

 70 species are credited only to Brazil. 



Scitamixales. — The four families of this series are all 

 tropical, two of them ( Musaceae and Zingiberaceae) being re- 

 stricted to the oriental tropics, and two (Cannaceae and Maran- 

 taceae) to the occidental. 



Oechidales. — The massing of orchids in the tropics of both 

 hemispheres is well known, but they are by no means restricted 

 to tropical conditions. As a rule, the numerous tropical genera 

 are not only restricted to hemispheres, but are often very local ; 

 while the temperate genera are represented in both hemi- 

 spheres; and the most northern genera even contain cosmopoli- 

 tan species. 



