﻿i8o 



REPRODUCTIVE STRUCTURES. 



originate on an adjacent series of xylem wedges in some approximately circular 

 position, or fairly definite order. 



FRUITS I AND III 



As already fully illustrated and described in Chapter VII, these two fruits are 

 bisporangiate and unexpanded, but bear nearly or wholly mature pollen. Their 

 ovulate stage of growth is an important starting point, since no example has 

 been found on trunk 214 of a developmental condition intermediate between the 

 present and the merely incipient stage of growth seen in the axes ix and VI, just 

 described. The structure of the ovulate cone being already understood, it is only 

 needed to repeat that the seed-stem region is but 0.9 mm. in thickness in fruit i, 

 and about twice as thick in the slightly older fruit in. (See plate xxxiv, photo- 

 graphs 1 and 2, and plate xxxvin, photograph 1, showing these strobili, which, 



according to our view, must in reality be 

 younger than the strobili next to be de- 

 scribed.) 



FRUIT VII. 



In this bisporangiate axis the stami- 

 nate disk, as may be seen on plate xxxix, 

 photograph 4, was evidently about to 

 expand. It has, however, failed of distinct 

 preservation, and the exact condition of the 

 (wilted) disk tissues at the point of insertion 

 is of interest to note, because just such 

 traces of tissue are more or less distinctly 

 present at the base of the fruits next to be 

 Xajt described, and have already been pointed out 

 in the ovulate cones of several other species. 

 {Cf. pages 129-131, 133, etc.). 



SSio 



Fig. 96. — Cycadeoidea dacotensis. T. 214. S. 520. 



Fr. VIII. Natural size. Tangential section to trunk 



made by cutting a cylindrical core in a slightly 



oblique direction, producing an elliptical form. 

 The section passes from the peripheral cortex above into the 

 basal armor below and cuts nearly transversely across the 

 bundle trace of two axes of fructification, No. 1 being cut 

 exacdy at its point of emergence from the cortex. The sur- 

 rounding and most nearly axillary leaf traces ( a. 1. 1. ) are also 

 indicated. The arrow indicates direction vertical to the 

 trunk. The two small inverted bundle segments inclosed 

 in peduncle trace II are unexplained, it not being understood 

 whether they are a reversion to older forms or simply leaf 



traces inclosed during the growth of the peduncle trace. clear in the transverse sections and the cor- 



responding longitudinal section, which is entire less the saw cuts. These sections 

 are shown in figure 97. The seed steins are a very little more advanced in growth 

 than in fruit 1. The former presence of a staminate disk is vouched for by the 

 presence of the remains of its basal portion, and it is also interesting to note the 

 presence in the more basal of the transverse sections of several synangia which lie 

 betzveen the cone and the surrounding ramenlu/u. These isolated synangia are indi- 

 cated in the figure. 



fruit x. 

 The summit of this finely preserved 

 conical-shaped young ovulate strobilus, as 

 in some of the other forms of about the 

 same stage of growth, projected a very little 

 beyond the surface of the armor. The 

 general features and structure are especially 



