THE PHYLOGENY OF GRASSES 269 



but one flower. Like the Paniceae the spikelets have the joint 

 below the empty glume. The best known example of the Oryzeae 

 is our common rice. 



The Phalaridean Line has also given rise to two small tribes, 

 the Zoysieae and the Tristegineae — each with about thirty spe- 

 cies, which are here omitted since they are scarcely known in 

 the United States. They are closely related to the Paniceae, 

 and may be included in that tribe with little difficulty. 



THE ANDROPOGONEAN LJNE 



The Andropogonean Line like the Phalaridean Line is dis- 

 tinguished by having spikelets with larger flowers at the top. 

 In this last line of development are found two tribes, the Andro- 

 pogoneae and the Maydeae, both distinguished by having many 

 spikelets in pairs (rarely in threes in Andropogoneae) one sessile 

 and the other stalked. 



The Andropogoneae which are very similar in appearance to 

 the Paniceae, but of solid stems and generally larger size, include 

 the beard grasses, blue stems, and sorghums. They are charac- 

 terized by having flowers arranged in pairs or threes, with the 

 central one perfect but the lateral ones pedicellate or stalked, 

 rudimentary, or wanting. 



The Maydeae have been evolved from the Andropogoneae by 

 the separation of the spikelets into staminate and pistillate 

 clusters. In Zea (our common corn) the ear is the cluster of 

 pistillate flowers; each grain of corn is a pistil and the silk (the 

 style and stigma) runs down from the tip of the ear to each kernel 

 of corn. The tassel at the top of the corn stalk is the cluster of 

 staminate spikelets, in which of course only stamens are pro- 

 duced. In both the ear and the tassel the flowers are arranged 

 in pairs, one stalked and one sessile, showing its derivation from 

 the Andropogoneae. 



THE PLANT WORLD. VOL. 15, NO. 11, NOVEMBER, 1912 



