602 
STRUCTURE AND LIFE HISTORIES 
Cycadeoidea by the celebrated geologist Buckland. The 
name of the order is derived from the genus-name, Bennet- 
tites. 1 Other forms, usually found as casts, are called 
Williamsonia, still others are known mainly as genera 
founded on leaf imprints. 
620. Cycadeoidea. In most of its purely vegetative 
characters, such as the anatomy of the stem and the 
FIG. 423. Cycadeoidea dacotensis (?). Photomicrograph of a young 
seed (X 15), showing a sterile scale on either side. Between them pro- 
jects the entire length of the tube through which the micropyle extends. 
The partially collapsed nucellus is distinctly shown in the center. (After 
Wieland.) 
structure of the leaves, Cycadeoidea resembled modern 
cycads, but its reproductive branches were character- 
istically lateral, which is one of the most fundamental 
characteristics of the higher seed-bearing plants of to- 
day. Only two modern cycads (Macrozamia and Bowenid) 
have lateral seed-bearing cones (Fig. 289). 2 Various 
1 Cycadeoidea Buckland = Benneltiles Carruthers. 
* The staminate cones of Zamia are lateral. 
