48 ACADEMIC BOTANY. 



the broad, flat stigma is closed, it has no stigmatic surface, 

 and the ovule is of course abortive — it produces no em- 

 bryo. The female flower (Fig. 50, C) is without stamens ; 

 its tegmen is prolonged to resemble a style, but is open 

 at top so that the ovule is still naked. The calyx-like 

 bract or sheath is broadly winged (Fig. 50, C). 



81. Gfymnospermous Growth is partially exogenous, — dif- 

 ferentiated into pith, wood, and bark ; but in the Cycads 

 the pith predominates, the growth is chiefly terminal (at 

 the apex, as in ferns) ; in nearly all the gymnospermous 

 Orders there is slight diiference between wood and bark, and 

 the terminal growth is strongest, making the trunk or main 

 stem excurrent (L. ex, through, out, curro, I run) ; that is, 

 the trunk runs through to the top, giving oif branches, but 

 keeping its integrity (Fig. 96). Observe four character- 

 istics : 



J. Naked mules; embryo many-celled, with radicle, 

 plumule, and two cotyledons, which in some genera are 

 many-parted ; 



II. Flowers without perianth; females usually on scales 

 which form cones ; always wind-fertilized ; 



III. Leaves parallel-veined (Cycas, Welwitschia), fork- 

 veined (Ginkgo), subulate (Juniper), or needle-shaped 

 (Pine) ; never net-veined. 



IV. Grrowth partially exogenous, but not fully so ; little 

 difference between wood and bark ; wood marked by cir- 

 cular disks (Fig. 215) ; stem simple (Cycas) or excurrent 

 (Pine, Fig. 95). 



