RANALES 389 



a natural unit of ten genera, of which Magnolia and Liriodendron are 

 best known. Though the Magnohaceae are considered apocarpous, 

 there is considerable fusion in tlie gynoecium. The carpels, at their 

 bases, are adnate to the receptacle along their margins (they are closed 

 in the proximal part in this way rather than by fusion of the margins) 

 and, in some taxa, connate, with the union so intimate that the lateral 

 traces of adjacent organs are fused. There is syncarpy in Pachylarnax; 

 in Talaiima, the fleshy carpels unite to form an Annona-Vike fruit. An 

 important specialization in this primitive family is unisexuality in 

 Kmeria. (Unisexuality is present in Drimijs also.) 



The family has been considered highly primitive because of its 

 simple flower structure — polymerous throughout, with all organs spirally 

 arranged on an elongate receptacle, with little connation and adna- 

 tion. But, like the other woody ranalian families, this family is spe- 

 cialized in certain characters. In the perianth, there is reduction in 

 number of tepals, with differentiation of a calyx and corolla, with sepals 

 and petals in whorls of three. The stamens show transition from nar- 

 row-laminar to anther-filament types (Figs. 49, 50 and 51); the carpels 

 show reduction from many to two or three, and the ovules from several 

 to one or two. The leaves are simple and pinnately veined, as is char- 

 acteristic of the woody Ranales. They have prominent stipules, variously 

 attached, below or adnate to the petiole. The stipules are early de- 

 ciduous, even from the petiole, where scars remain. 



In the presence of occasional accessory flowers in several genera and 

 of clusters of flowers ("axillary") in Michelia, there is evidence that the 

 usually solitary flowers represent reduction from an inflorescence. (In 

 the Winteraceae also, there is reduction of the inflorescence, from a 

 complex type to a solitary flower — Zijgogijnum.) 



The perianth provides an excellent example of the differentiation of 

 a corolla from tepals — in contrast with the more common origin from 

 staminodes — and of the origin of the whorled arrangement in floral 

 organs. The androecium shows a series of stages in the phylogenetic 

 modification of a laminar stamen. The long, adaxial microsporangia, 

 characteristic of primitive families, are nearly median on the sporophyll 

 in some taxa. With the narrowing of the sporophyll, they come to lie in 

 pairs, closer and closer to the margins and, ultimately, to take a "mar- 

 ginal" position, with dehiscence extrorse (Liriodendron, species of 

 Michelia). The various taxa show the development of a slender filament 

 from the basal part of the broad primitive sporophyll, and of a terminal 

 appendage from the distal part. The appendage is lost in Liriodendron. 

 (Within the family, the stamen of Liriodendron is of high type in the 

 possession of a long, subterete filament, the absence of a terminal ap- 

 pendage, and extrorse dehiscence. The laminar nature of the filament is 



