CrCADEM. 



5^3 



the lamina terminates above, points to a dichotomdus branching of the leaf, the rachis 

 of which may therefore be considered as a sympodium composed of the basal 

 portions of the successive bifurcations, while the lateral leaflets represent the bifur- 

 cations of th€ lamina of the leaf, the growth of which is arrested and flattened. 

 The whole leaf would therefore be a dichotomous cymose branch-system. Re- 

 searches into the history of its development are however wanting, as in the case of 

 the branching of the stem and root. 



The Flowers of the Cycadeae are always dioecious, and the plants are therefore 

 either male or female. Both kinds of flowers appear at the summit of the stem, 

 either singly, as in Cjycas, as terminal flowers of the primary stem, or in pairs or 

 larger numbers as in Zamia muricaia and Macrozamia spiralis^ where they may 

 perhaps be regarded as metamorphosed bifurcations of the stem\ The flower con- 

 sists of a strong conical elongated axis, sometimes supported on a naked peduncle, 

 but densely covered in other parts by a large number of staminal and carpellary 

 leaves arranged spirally. 



In Cycas the female flower is a rosette of foHage-leaves which have under- 

 gone but slight metamorphosis (Fig. 343), the apex of the stem developing again 

 first of all scale-leaves, and then new whorls of foliage-leaves ; the stem, therefore, 

 grows through the female flower, thus furnishing an instance of proHfication. The 

 separate carpels are, indeed, much smaller than the ordinary foliage-leaves, but are 

 essentially of the same structure; the lower pinnae are replaced by ovules, which 

 attain, even before fertilisation, the magnitude of a moderate-sized ripe plum, the 

 fertilised seed acquiring the dimensions and the appearance of a moderate-sized 

 ripe apple, and hanging quite naked on the carpel. Whether the male flower of 

 Cycas also exhibits proHfication I do not know, and it seems improbable ; the very 

 numerous staminal leaves are much smaller, 7 to 8 cm. long, and undivided; they 

 expand considerably from a narrow base and terminate in an apiculus. They are 

 furnished on the under side with a number of densely-crowded pollen-sacs ; the 

 whole flower is from 30 to 40 cm. long. 



The male and female flowers of the remaining genera of Cycadese resemble 

 fir-cones externally. The comparatively slender floral axis rises as a rachis on a 

 short .naked peduncle, and on this are seated the numerous staminal or carpellary 

 leaves (Fig, 344). The axis terminates with a naked apex which undergoes no 

 further development (Fig. 344 D). The stamens are, indeed, but small in comparison 

 to the foliage-leaves of the same plant, but are, nevertheless, the largest which 

 occur anywhere among Phanerogams. In Macroza?nia, as in Cycas, they are from 

 6 to 8 cm. long, and as much as 3 cm. broad ; they spring, with rather a narrow 

 base, from the floral axis, and expand into a kind of lamina, terminating in an 

 apiculus {Macrozamia) or in two curved points {Ceratozamia), or the lower part of 

 the stamen is thinner and stalk-like and bears a peltate expansion {Zamia), They 

 are also distinguished from the stamens of most other flowering plants by their 



' The hypothesis that the male flower of Cyca& Rumphii is one, the leaf-bud by which the stem 

 is prolonged the other bifurcation of the dichotomising apex of the stem, is not supported by 

 De Bary's recent researches. [According to Warming (Joe. cit.) all the flowers are probably terminal; 

 possibly the male flower (in Ceratozamia longifolia) is produced on a branch of a dichotomy of the 

 stem : it is certainly not borne on a lateral branch.] 



