CLASSIFICATION OF ARCHICHLAMYDEAE 247 



much in common with the Ranales, especially the line con- 

 taining Ranunculaceae. However, it has reached a much higher 

 development in the more frequent occurrence of syncarpy, and 

 also of perigyny and epigyny, and especially in the remarkable 

 development of zygomorphy among the Leguminosae. Disre- 

 garding the smaller families, the Saxifragaceae may be regard- 

 ed as the beginnings of the alliance, originating in the Ranales, 

 and diverging toward Podostemonaceae in one direction and 

 Rosaceae-Leguminosae in the other. It has long been known 

 that there is no real distinctive character separating Saxifraga- 

 ceae and Rosaceae ; and the transition from the latter family to 

 the Leguminosae is easy. Rosaceae are characterized by actino- 

 morphic flowers and several carpels; while Leguminosae have 

 zygomorphic flowers and a single carpel ; but there are members 

 of the two families that exactly reverse these distinctions. There 

 seems to be a general plexus formed by the Rosa tribe of Rosa- 

 ceae and the Mimosa tribe of Leguminosae, which is not very 

 far removed from the Ranunculaceae among Ranales. Out of 

 the Rosa tribe the two very distinct lines of drupe-forms and 

 pome-forms have diverged; while the Mimosa tribe, with its 

 actinomorphic flowers and numerous usually free stamens, leads 

 through the Caesalpinia tribe, with its actinomorphic or zygo- 

 morphic flowers and free stamens, to the Papilio tribe with its 

 strongly zygomorphic flowers and coalescent stamens. 



The culmination of the alliance is of course the elaboration 

 of zygomorphy, the Leguminosae dominating in this regard 

 among Archichlamydeae, as do the Orchidaceae among Monoco- 

 tyledons, and the Personales among Sympetalae. 



In the preceding related alliances, from Ranales to RosaL ■-, 

 the cyclic character of the flower is not fully established, every 

 line of development having spiral members. In the following 

 alliances, however, the cyclic character is fully established. 



XIX. Geraxiales. — This includes Geraniaceae, Oxalida- 

 ceae, Tropaeolaceae, Linaceae, Humiriaceae, Erythroxylaceae> 

 Zygophyllaeeae, Cneoraceae, Rutaceae, Simarubaceae, Bursera- 

 ceae, Meliaceae, Malpighiaceae, Trigoniaceae, Vochysiaceae, 

 Tremandraceae, Polygalaceae, I Hchapetalaceae, Euphorbiaceae, 

 and Callitrichaceae, together containing about 9,160 species, 

 the large families being Euphorbiaceae with 4,140 species, Ru- 

 taceae with 910, Meliaceae with 753, Malpighiaceae with 700, 



17 



