Origin of Angiosperms 207 



bracts, forming collectively a kind of perianth and completely en- 

 closing the essential organs of reproduction. The latter consist of 

 a whorl of stamens, of extremely elaborate structure, surrounding a 

 central cone or receptacle bearing numerous ovules. The stamens 

 resemble the fertile fronds of a fern ; they are of a compound, 

 pinnate form, and bear very large numbers of pollen-sacs, each of 

 which is itself a compound structure consisting of a number of com- 

 partments in which the pollen was formed. In their lower part the 

 stamens are fused together by their stalks, like the "monadelphous" 

 stamens of a mallow. The numerous ovules borne on the central 

 receptacle are stalked, and are intermixed with sterile scales ; the 

 latter are expanded at their outer ends, which are united to form a 

 kind of pericarp or ovary-wall, only interrupted by the protruding 

 micropyles of the ovules. There is thus an approach to the closed 

 pistil of an Angiosperm, but it is evident that the ovules received 

 the pollen directly. The whole fructification is of large size ; in the 

 case of Cycadeoidea dacotensis, one of the species investigated by 

 Wieland, the total length, in the bud condition, is about 12 cm., 

 half of which belongs to the peduncle. 



The general arrangement of the organs is manifestly the same 

 as in a typical Angiospermous flower, with a central pistil, a sur- 

 rounding whorl of stamens and an enveloping perianth ; there is, 

 as we have seen, some approach to the closed ovary of an Angio- 

 sperm ; another point, first discovered nearly 20 years ago by Solms- 

 Laubach in his investigation of a British species, is that the seed 

 was practically " exalbuminous," its cavity being filled by the large, 

 dicotyledonous embryo, whereas in all known Gymnosperms a large 

 part of the sac is occupied by a nutritive tissue, the prothallus or 

 endosperm ; here also we have a condition only met with elsewhere 

 among the higher Flowering Plants. 



Taking all the characters into account, the indications of affinity 

 between the Mesozoic Cycadophyta and the Angiosperms appear 

 extremely significant, as was recognised by Wieland when he first 

 discovered the hermaphrodite nature of the Bennettitean flower. 

 The Angiosperm with which he specially compared the fossil type 

 was the Tulip tree (Liriodendron) and certainly there is a remarkable 

 analogy with the Magnoliaceous flowers, and with those of related 

 orders such as Ranunculaceae and the Water-lilies. It cannot, of 

 course, be maintained that the Bennettiteae, or any other Mesozoic 

 Cycadophyta at present known, were on the direct line of descent 

 of the Angiosperms, for there are some important points of difference, 

 as, for example, in the great complexity of the stamens, and in the 

 fact that the ovary-wall or pericarp was not formed by the carpels 

 themselves, but by the accompanying sterile scale-leaves. Botanists, 



