SPERMATOPHYTES 279 



Archichlamydeae 



This vast group contains a maze of forms whose relationships are very 

 confusing. Over 61,000 species and 180 families are recognized, which 

 are grouped into 26 great alliances. Archichlamydeae include primi- 

 tive angiosperms, and although they are prevaihngly spiral, the cyclic 

 condition, with a definite number in all of the floral members, is estab- 

 lished in several of the higher alliances. It would be unprofitable to 

 name all of the aUiances, for many of them would suggest nothing to 

 the elementary student. Some of the more significant will be selected 

 for brief description, and the others grouped. 



1-12. (26 families, 5900 species.) — This group of alliances is espe- 

 cially puzzling as to relationships. They are regarded as relatively 

 primitive forms, and include many of the most common trees, as 

 willows, walnuts, beeches, oaks, etc. Many of them were formerly 

 grouped as Amentiferae, a name referring to the characteristic flower 

 cluster called ament or catkin, a cluster perhaps most familiar in the 

 willows and alders. The flowers are naked or have a bractlike perianth, 

 the floral numbers are generally indefinite, and wind poUination pre- 

 vails. This assemblage does not seem to be related to any of the higher 

 alliances. 



13, 14. (11 families, 4070 species.) — This is another apparently iso- 

 lated group, including such plants as smartweed (Po/y^owMw), pigweed 

 {Amaranthus and Cheno podium), pinks (Caryophyllaceae), etc. In 

 structure the flowers range from a bractlike perianth to distinct sepals 

 and petals, and are mostly cyclic, three, four, and five being the pre- 

 vailing floral numbers. Insect pollination is established only among 

 the pinks. 



15. Ranales (16 families, 4050 species). — This is recognized as the 

 great genetic alliance, which means that the higher alliances are thought 

 to have been derived from it. FamiKar families are the crowfoots or 

 buttercups (Ranunculaceae), the water lihes (Nymphaeaceae), and the 

 magnolias (Magnoliaceae). There is a distinct calyx and corolla; the 

 flowers are hypogynous; and the numerous carpels form separate pistils 

 {apocarpous). Although the cyclic number is often evident in the 

 calyx and corolla, the stamens and carpels at least usually retain the 

 spiral condition and are indefinitely numerous. By some it is thought 

 that the Ranales are the most primitive Archichlamydeae, not only 

 giving rise to the other dicotyledons, but also to the monocotyledons. 



