THE EVOLUTION OF PLANTS 



6o 3 



FIG. 424. Cycadoidea Wielandi. At left, a finely preserved trunk 

 bearing many ovulate cones with seeds approaching maturity, and a lesser 

 number of either young or abortive cones. /', Receptacle of a shed or 

 non-preserved cone with surrounding bracts yet present; /", two cones 

 broken away during erosion, with a portion of the basal infertile pedicel 

 yet remaining; m, four cones eroded down to the surface of the armor, 

 in this instance about or a little beneath the level of the lowermost 

 seeds; y, three of the dozen or more very young cones, in some cases known 

 to be simply ovulate and to be regarded as having aborted or else as be- 

 longing to a later and sparser series of fructifications than the seed-bearing 

 cones present, the latter unquestionably representing the culminant fruit- 

 producing period in the life of this cycad; s (over lower arrow), the ovulate 

 strobilus shown at right in its natural position, this photograph having 

 been made before the cone was cut out by a cylindrical drill. X about 

 14. At right, longitudinal section of the small ovulate strobilus cut from 

 its natural position on the trunk as denoted by the arrow s, in photograph 

 i. c (upper arrow), seed with dicotyledonous embryo preserved, cotyle- 

 dons being similarly present in the lowermost seed on the left-hand side 

 of the strobilus; s, traces of hypogynous staminate disk; b, bracts; /, leaf 

 bases. X about y. (After Wieland.) 



