24S MORPHOLOGY OF ANGIOSPERMS 



Polygalaceae with 607, Geraniaceae with 455, Oxalidaceae with. 

 330, and Burseraceae with 320. 



This cyclic alliance begins with those families that are iso- 

 carpic and extends to those in which a reduction in the number 

 of carpels is prevalent. It is chiefly distinguished from the 

 Sapindales, with which it is parallel and very closely allied, 

 by the orientation of the ovules, the raphe of the anatropous 

 ovules being ventral in Geraniales and dorsal in Sapindales. 

 Just the significance of such a character in distinguishing great 

 genetic alliances is not clear, but its constancv is in its favor. 

 Three lines of development are evident, the most prominent 

 beginning with Geraniaceae, including the zygomorphic and 

 anisocarpic Tropaeolaceae and the completely syncarpic Lina- 

 ceae and its allies, and ending in Cneoraceae to Meliaceae with 

 oil-cells and highly differentiated tissues. Another line is Mai- 

 pighiaeeae to Vochysiaceae, characterized by oblique zygomor- 

 phy ; while Polygalaceae with its strongly zygomorphic flowers, 

 Dichapetalaceae, and Euphorbiaceae, show no surviving fea- 

 tures in common. The affinities of these last three families 

 are extremely doubtful, and those of Callitrichaceae are even 

 more so. 



XX. Sapindales.* — This includes Buxaceae, Empetra- 

 ceae, Coriariaceae, Limnanthaceae, Anacardiaceae, Cyrillaceae, 

 Pentaphylaeeae, Corynocarpaceae, Aquifoliaceae, Celastraceae, 

 Hippocrateaceae, Stackhousiaceae, Staphyleaceae, Icaeinaceae, 

 Aceraceae, Hippocastanaceae, Sapindaceae, Sabiaceae, Meli- 

 anthaceae, and Balsaminaceae, together comprising about 3,125 

 species, the large families being Sapindaceae with 1,040 species, 

 Celastraceae with 425, Anacardiaceae with 395, Balsaminaceae 

 with 300, and Aquifoliaceae with 285. 



As among Geraniales, the alliance begins with isocarpic 

 forms and passes to those in which the number of carpels is 

 reduced, and in the higher families zygomorphy is attained. 

 The orientation of the ovules that separates this alliance from 

 the Geraniales was referred to under that alliance. Engler rec- 

 ognizes so many lines of development among Sapindales that 

 the alliance seems to be well broken up. and the different mem- 

 bers not clearlv related to one another. 



* Sometimes called Celastrales. 



