2C-J 



MORPHOLOGY 



veins that branch dichotomously, except in certain forms with very 

 narrow leaves. In some forms the leaves are short and obovate, sug- 

 gesting those of Gink- 

 goales. The structure of 

 the leaves is like those 

 of the cycads, with the 

 very characteristic meso- 

 phvll (see p. 193). In 

 form, therefore, the leaves 

 in general resemble those 

 of the conifers ; but in 

 structure they resemble 

 those of the cycad line. 



Strobili. —The strobili 

 are small and monospo- 

 rangiate, both kinds of 

 strobili usually occurring 

 on the same plant (monoe- 

 cious), characters which 

 belong to the conifers. 

 They occur in clusters 

 on lateral branches (fig. 

 461), and both kinds are 

 sheathed by bracts. 



Slaminate. — The stam- 

 inate strobilus is made up 

 of spirally arranged sterile 

 bracts, among which the 

 stamens occur, either soli- 

 tary or grouped near the 

 apex (fig. 462). Each 

 stamen is a slender stalk 

 bearing a terminal cluster 

 of three to six erect spo- 

 rangia with longitudinal 

 dehiscence. It is only among the Cycadofilicales that such terminal 

 and erect microsporangia are found (cupule type, see p. 184). 



Ovulate. — The ovulate strobilus is made up of conspicuous over- 

 lapping bracts, in whose axils short branches appear, each of which 



Fig. 461. — Restoration of Dorycordaites, one of 

 the Cordaitales, showing the branching habit, the 

 simple, elongated, parallel-veined leaves, and the 

 clusters of strobili borne on lateral branches. — After 

 Grand 'Eury. 



