CYCADALES 



[CH. 



unusual (fig. 378; fig. 381, B). Many Cycads are geophilous and 

 have short tuberous stems (figs. 383, 395, la; 396, E): the genus 

 Zamia includes a few epiphytic forms'. The typical cycadean 

 stem is covered with persistent petiole-bases with or without an 

 admixture of smaller scale-leaf bases (figs. 379, 380), while in 

 several species a transversely wrinkled or irregularly fissured 

 periderm forms the superficial tissue (figs. 381, B; 383). The 

 foliage-leaves are relatively large and, with the exception of the 

 bipinnate fronds of Bowenia (fig. 391), they are always pinnate. 

 The fronds usually form a terminal crown (figs. 377, 379) and 



Via. 380. Cycas circinalis. Stem showing alternate zones of leaf-bases (F) and 

 scale-leaf bases (S ). (From the Encyclopaedia Britannica. ) 



as many as 100 may be produced from one bud. In Zamia 

 pygmaea^ the fronds are only 10 — 12 cm. long, but in some cycads 

 they reach a length of several metres. On both young foliage- 

 leaves and scale-leaves long and very rarely branched^ unicellular 

 hairs (fig. 396, N) form a characteristic feature and take the place 

 of the ramental scales of the majority of ferns. The apex of the 

 stem shown in fig. 386, A is covered with a mass of woolly hairs 

 and several scale-leaves are seen on the lower part of the bud. 



All recent Cycads are dioecious. The reproductive shoots, 

 except the megasporophylls of Cycas — which have departed to a 

 less extent than those of other genera from the foliage-leaf plan 

 (fig. 381, A; fig. 392, A— C) and are borne in a terminal cluster 



'■ Wieland (06) p. 190. ^ Botanical Magazine, Tab. 1741. 



' Matte (04) PI. xi. fig. 185 (Microcycas). 



