388 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1917. 



which a number of Thrinax seeds occur. Seeds of the royal palm 

 may have found their way to the park in the same way, dropped by 

 migrating birds from Cuba. In southern Florida trees of this 

 species as well as those of the cabbage palm and the introduced 

 coconut are sometimes used with great effect to form avenues. It is 

 interesting to note that the leaves of the cabbage palm, though usually 

 called fan-shaped, really have a short, decurved midrib (fig. 11). 

 This feature, together with certain peculiarities of the inflorescence, 

 leads Mr. O. F. Cook of the Bureau of Plant Industry to separate 

 several species usually included under Sabal into a distinct genus 

 which he has named Inodes. 



TIXELAND FLORA. 



The only pine growing in the vicinity of Paradise Key is Pinus 

 caribaea (pi. 29). This is one of the species which gives its name to 

 the Isle of Pines on the south coast of Cuba. It covers vast areas of 

 southern Florida (pi. 30), accompanied by an undergrowth pecul- 

 iarly its own. Next to the saw palmetto the most remarkable plant 

 of the pinelands is a cycad, Zamia floridana, from which the Semi- 

 noles make a starch, commonly called coontie, or Florida arrowroot. 



The ancestors of this plant and its congeners can be traced back to 

 the giant cycads of the Carboniferous age. Among its relatives are 

 the " sago palms," Cycas circindlis and Cycas revoluta, so well known 

 to horticulturists. 1 Closely allied species of the same genus occur in 

 the West Indies, and of related genera in Mexico, Central America, 

 and Africa. All of them are remarkable for their peculiar method of 

 cross- fertilization ; and nearly all of them are valuable as sources of 

 food. 



Zamia and its allies occupy a place intermediate between flower- 

 ing plants and ferns. Like the former, they bear fruit with a true 

 endocarp or seed ; but, like the latter, their sexual propagation is ac- 

 complished by means of spermatozoids provided with movable cilia, 

 resembling those of animals. The male and female plants are easily 

 distinguished. The inflorescence of the male plant (pi. 31) is in the 

 form of an erect cone, shaped somewhat like an ear of maize and 

 composed of scales which bear on their under surface numerous 

 pollen sacs. That of the female plant (pi. 32), much thicker and 

 relatively shorter, is composed of broad scales, each bearing a pair 

 of ovules quite devoid of any protective covering. The pollen, 

 borne by the wind, settles on the ovules, and sends down a tube into 

 the tissue of the nucellus. Archegonia are formed; egg cells de- 

 velop, and in the pollen tube are produced spermatozoids which 

 fecundate the egg. The fertilization of Zamia floridana was studied 



1 See Bailey's Standard Cyclopedia of Horticulture, 2 : 931 to 933. 1914. 



