RANALES 385 



the important features of the Winteraceae — in part additional to those 

 commonly used in taxonomic characterization — are the following. 



The flowers of Drimtjs show advance in the development of unisexual 

 from perfect flowers: the New World species (section Wintera) are 

 bisexual; the Old World species (section Tasmannia) are polygamo- 

 dioecious or unisexual. A primitive perianth shows stages in speciahza- 

 tion. The calyx is calyptratc; the sepals are bractlike but connate. The 

 petals range from scalelike to petaloid, with reduction from several to 

 two, and the position of the two produces zygomorphism. The stamens 

 show stages in specialization from a broad, laminar type to wedge- 

 shaped and subterete. The pairs of microsporangia, commonly sub- 

 marginal and distal, seem to represent stages in the differentiation of an 

 anther (Fig. 49). The pairs of sporangia are lateral or nearly so, an 

 advance over the median position in laminar stamens. Dehiscence is 

 latrorse to extrorse, with most genera extrorse. The pollen is borne in 

 permanent teti-ads — an advanced character — present elsewhere in the 

 Ranales only in Lactoris. The stamens of most of the Winteraceae, in 

 contrast to those of most other ranalian families, lack the protruding 

 connective, characteristic of primitive stamens (only BelJioJum has an 

 extended connective). The absence of this primitive character, promi- 

 nent in most ranalian families, is perhaps related to an unusual type of 

 modification, in this family, of the ancestral laminar sporophyll — the 

 transfer of the sporangia from a median to a subterminal or terminal 

 position at the end of the connective. The pollen grains are of the primi- 

 tive monocolpate type, with the germinal aperture reduced to a pore. 

 Development within the androecium is centrifugal, a character only re- 

 cently recognized in the Winteraceae. Nectaries are absent, and no 

 description of the method of pollination has been found. 



The carpels are conduplicate, not differentiated into ovary, style, and 

 stigma, and range from long-stipitate to sessile. Evidence from com- 

 parative form and from anatomy in the Ranales and Rosales supports 

 the view that the carpel is primitively stipitate. (The stipe is, ana- 

 tomically, a part of the carpel, not of the receptacle, as sometimes 

 described.) The carpels are "open" — not sealed — at pollination time in 

 Drimys, section Tasmannia, and in species of Buhhia and Exospermum; 

 in other taxa, they are open through only part of their length. The 

 pollen is received on a longitudinal stigmatic crest, a ventral ridge 

 formed by the approximated edges of the folded carpel lamina (Fig. 

 83). The somewhat flaring, unfused edges of the lamina form a two- 

 lobed or "double" ridge. This ridge is covered on both dorsal and 

 ventral surfaces by papillose hairs, among which the pollen germinates. 

 In the more primitive species of Drlmijs and Buhhia, the stigmatic 

 ridge runs the entire length of the carpel— is taxonomically described 



