ri4 



MORPHOLOGY OF GYMNOSPERMS 



and that it is not a symbiont, but rather a parasite against which the 

 cell reacts as a phagocyte. 



2. The spore-producing members 



THE MICROSPORANGIUM 



All the living cycads are strictly dioecious. The staminate strobili 



usually occur singly in the 

 center of the crown (fig. 95), 

 but several may appear at 

 once. In Macrozamia Moorei 

 (83), thirty to forty cones are 

 not exceptional, and even a 

 hundred have been counted. 

 The first cone is terminal 

 and subsequent ones lat- 

 eral, except in Encephalartos, 

 Macrozamia, and Bowenia, 

 where all cones are axillary. 

 Except in case of axillary 

 cones, the apical meristem is 

 used up in the production of 

 the cone, and a new meristem 

 appearing at the base con- 

 tinues the growth, pushing 

 aside the cone and assuming 

 the erect position. Miss F. 

 Grace Smith (56) has shown 

 that the trunk of Zamia is 

 really a sympodium, the pro- 

 duction of a cone being fol- 

 lowed by the development of 

 a branch which quickly be- 

 comes erect, so that the trunk 

 does not appear to be branched 

 (figs. 96-98). In Encepha- 

 FiG. 95. — Dioon edule: upper portion of lartos Friderici-GuiUelmi and 



pkrit with staminate cone; photographed at -^ ^ AUensteinii PeARSON 

 Chavamllo, Mexico, aeptember igoo; one- 

 third natural size.— After Chamberlain (63). (47) has described a groUD of 



