THE ANGIOSPERMAE 



1243 





i^ 



Fig. 1 198. — Degeneria vitiensis. Longitudinal sections through carpels. A, Outline 

 showing position of the stigma and its extension inwards to the line of ovules, 

 shown as small circles. Note exceptional degree of branching of the dorsal bundle 

 and the o\-ules supplied by branches of a bundle coming from the dorsal side of 

 the carpel. B, Vascular system showing relatively weak, unbranched ventral bundles 

 and ovules supplied by branches from the dorsal system. {After Szcamy.) 



is to say, in a number of characters, among which is the absence of union 

 between the carpel margins. The carpels are closely set in two trimerous 

 whorls and resemble those of Degeneria in form but with the marginal 

 stigmas confined to the summit of a short, stylar prolongation. Although 

 the absence of marginal union is exceptional among free carpels it is a 

 commonplace among united carpels. The paracarpous condition, in fact, 

 exists because the margins of the constituent carpels are united to those of 

 their neighbours rather than to each other, so that each carpel is completely 

 open inwards. 



It has not been our practice in this book to refer to teratological abnor- 

 malities, which are too various and peculiar to be adequately considered in a 

 general text. An exception may be made here, however, in referring to the 

 intergrades or combinations of stamen and carpel which have been recorded 

 in a number of plants; e.g., Ranunciihis, Salix and Podophyllum. Some of 

 these intergrade organs are staminate but in addition to pollen-sacs they 

 bear ovules, either superficially or partially enclosed; others are apparently 

 carpellate but bear pollen loculi as well as ovules. Rainio has maintained 

 that there is order in this seeming disorder and that the pollen-sacs and 

 ovules develop at difTerent and definite points on the appendages, which he 

 regards as truly amphisporangiate sporophylls. No change of fertility is 

 evident; both the pollen grains and the ovules, though formed in novel 



