﻿CHAPTER VIII. 



YOUNG FRUCTIFICATIONS. 



No more fascinating problems are involved in the study of the various features 

 of the Cycadeoidese than those dependent on a knowledge of entire series of young 

 strobili ; for it is to the young fruits that one must turn if he would know much 

 about habits of growth and modes of fructification in these interesting plants, the 

 form of bisporangiate development seen in them being precisely the one capable of 

 the most gradations of moncecism, dicecism, and bisexuality. It is hence a very 

 fortunate fact that many of the trunks from the Black Hills bear finely conserved 

 young fruits by the score and hundred. But this wealth of fossil evidence carries 

 with it a heavy responsibility measured in time and resources for investigation. 

 It therefore need surprise no one if there be now presented but a mere prodromus 

 of the facts relating to the widelv varied sex differentiation undoubtedly exhibited 

 by the Cycadeoidese. 



CYCADEOIDEA SP. (SECTIONS 410 AND 411.) 

 (Figure go, n.) 



The description of young or but partly mature forms of fructification may be 

 begun by a brief notice of a quite small isolated fruit from the Minnekahta cycad 

 locality. The longitudinal and transverse sections numbered 410 and the accom- 

 panying serial transverse sections numbered 411 clearly display the larger struc- 

 tures of this small and young strobilus. The slender peduncle bears an elongate 

 cylindrical and slightly tapering apical ovulate cone 15 mm. long by only 6 mm. 

 in diameter, surrounded by very young bracts. The sporophyll zone is already a 

 millimeter and a half in thickness, and the comparatively large ovules, preserved 

 in outline only, are seated on such short pedicels as to appear sessile or nearly so. 

 An additional feature of especial importance is the presence just above the upper- 

 most bracts of a basal disk or collar which, after rising to the height of a millimeter 

 or two, is interrupted by clear and structureless silica, but is again indicated by 

 unmistakable traces farther up on the sides of the fruit. The relation of parts is 

 clearest in the transverse sections where the disk appears as a continuous band 

 surrounding the ovulate cone. Above the summit of the ovulate cone there is 

 inside the bracts a naturally stained capping of nonconserved tissue which evidently 

 belonged to the disk. (See figure 90, 11, and plate xi.iv, photographs 1 and 2.) That 

 there is indicated here a young unexpanded ovule and disk-bearing strobilus can 

 not be doubted. That under favorable circumstances seeds would have been produced 

 is also evident. But whether microspores w T ould have been produced by the disk or 

 not, and therefore whether the parent plant was bisexual, monoecious, or dioecious, 

 could not be affirmed on the basis of the present single and isolated fruit alone. 



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