422 A TEXTBOOK OF GENERAL BOTANY 
excurrent form of growth. The branches are of two kinds, long 
branches and short branches with limited growth. The only leaves 
on the long branches are scale leaves (Fig. 479), a feature not char- 
acteristic of all conifers. The short branches arise in the axils of 

Fic. 477. Three-hundred-foot redwood, 
Humboldt County, California 
the scale leaves and bear 
needle-shaped green leaves, 
singly or in clusters (Fig. 
479). The short branches 
are deciduous, being shed 
with the leaves (Fig. 479). 
Megasporangium and 
female prothallus. The 
megasporangia (ovules) 
are produced in cones 
(Fig. 479). The cones 
terminate special short 
branches. Each sporangia- 
bearing component of the 
cone consists of a bract 
and above this an ovulit- 
erous scale with two meg- 
asporangia (Fie. 479). 
This compound structure 
does not seem to be a 
simple megasporophyll, 
but there is great dif- 
ference of opinion as to 
its morphological nature. 
The ovuliferous scales are 
the conspicuous scales in 
the mature cone. The megasporangia occur near the base of the 
ovuliferous scale and are directed toward the central axis of the cone. 
The megasporangium resembles that of the cycads in that it con- 
sists of a nucellus surrounded by a single integument (Fig. 451). 
A megaspore mother cell is formed within the nucellus and di- 
vides to form a row of four megaspores (Figs. 451, 452). 
