236 MORPHOLOGY OF ANGIO!>PERMS 



ceae and Centrolepidaceae, constitute the main part of the old 

 group Enantioblastae, characterized by the orthotropous ovules. 



The Rapateaceae, chiefly South American, have a distinct 

 calyx and corolla, anatropous ovules, and small embryos. 



The Bromeliaceae, the great epiphytic family of the Ameri- 

 can tropics, have a distinct calyx and corolla, anatropous ovules, 

 and larger elongated embryos. 



The Commelinaceae, in addition to the distinct calvx and 

 corolla, show a tendency to zygomorphy. This family has the 

 orthotropous ovules and small embryos of the Enantioblastae, 

 but the characters given, as well as the habit and inflorescence, 

 seem to forbid that alliance. 



The Pontederiaceae and the Australasian Philvdraceae 

 have long cylindrical embryos, a general tendency to a reduced 

 number of stamens and carpels, and in the latter family sym- 

 petaly. 



VIII. Liliales.* — The nine families of this alliance are 

 Juneaceae, Stemonaceae, Liliaceae, Haemodoraceae, Amarylli- 

 daceae, Velloziaceae, Taccaceae, Dioscoreaceae, and Iridaceae, 

 together comprising almost 5,000 species. The largest families 

 are Liliaceae with nearly 2,500 species, Iridaceae with more 

 than 1,000, and Amaryllidaceae with nearly 900. 



This great alliance may be regarded as containing the typ- 

 ical highly developed Monocotyledons. It is characterized by 

 a conspicuous development of the perianth and a prevailing 

 entomophilous hain't. The endosperm cells are thick-walled and 

 in general contain oil rather than starch, resulting in an endo- 

 sperm that is not " mealy," as in the Farinales. The Junea- 

 ceae, Haemodoraceae, and Velloziaceae are exceptions in pro- 

 ducing a starch-containing endosperm, but the cells do not be- 

 come dissociated. In passing from the lower members of the 

 series to the higher there is a transition from an undifferenti- 

 ated scarious perianth to a differentiated and petaloideous one; 

 and from hypogyny to epigyny, the four lower families being 

 hypogynous and the five higher epigynous. 



The sequence of families begins with the Juneaceae, which 

 with their grass-like habit, scarious perianth, and starchy en- 

 dosperm, may be fairly regarded as intermediate between Fari- 



* Liliiflorae of Engler. 



