﻿OVULATE CONES. 



129 



CYCADEOIDEA TURRITA. 

 (Trunk 364, section iij.) 



A cycadeoidean fruit closely resembling those of C. Wielandi (trunk 393) is 

 shown in figure 64. This fruit was cut from a fragmentary trunk, and as divested 

 of its surrounding bracts affords an excellent example of the appearance which many 

 of these seed cones doubtless had when shed. An exact idea of the scars that would 

 have been left by any such dehiscent fruits is to be had from many trunks, and 

 more especially from 131 and 745, although the fruit scars of these and various 

 similar specimens are more directly due to partial preservation, or to the subsequent 

 exigencies of erosion from the beds in which these beautiful plants and fruits have 

 been preserved since Jurassic time. In the fruit before us the outer layer of the 

 testa of the fairly large seeds is especially well preserved (cf. fig. 62), as are also the 



sieve-like to scalariform elements of the terminal parts 

 of the receptacle, the bract bases, and the peripheral 

 interseminal scales. Also, as in the case of various 

 similar cones, there is between the uppermost of the 

 spirally arranged bracts and the basal periphery of the 

 ovulate strobilus proper an annular shoulder which 

 receives a bundle supply from the main woody cylinder 

 of the peduncle, as indicated in photomicrograph 2, 

 plate xxxi. The condition of the tissues of this annular 

 region shows very plainly that an earlier abortive or 

 much more likely a functional disk was attached 

 hypogynously to the ovulate cone. The dehiscent line 

 is annular, since in all longitudinal sectious it is indi- 

 cated in the same relative position on both sides of 

 the peduncle, the condition in the fossil suggesting the 

 wilting down of an earlier attached disk rather than a 

 direct splitting off. This, indeed, is almost the only 

 fact that might at first be construed as indicating an 

 abortive condition of the early growth borne by the 

 annular shoulder ; for one might expect stamiuate 

 growths to be shed Dodily, much as are the stamens of 

 Liriodendron. The isolated William sonia disks with 

 sharply outlined insertion are also to be recalled in 

 this connection. Yet it is to be noted that, although 

 pollen-producing and fused basally into a disk, the 

 staminate fronds of the Cycadeoidese were in appearairce and texture essentially 

 fern fronds ; and ever}- botanical student is familiar with the slow wilting of fertile 

 fronds such as those of Osmunda, the stringy basal portions of which remain 

 behind for many months after the ripening of the spores. Moreover, in these 

 fossil fruits there is often in the slight remnant of the earlier growth from the 

 annular shoulder a most striking resemblance to the wilted tissue of fern fronds, as 

 well as partially conserved bundles. 



Fig. 64. — Cycadeoidea lurrila. 

 T. 364. S. 113 :■ I 1 ,. 

 Longitudinal section through 

 ovulate strobilus. showing 

 shoulder left by the dehiscence 

 of a staminate disk (s), and 

 the bases of several of the 

 enveloping bracts (b). (See 

 photograph 2, Plate XXIV.) 



