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RELATIONSHIPS. 



The Floridian species are Zamia pumila and Z. floridana, these being the only 

 cycads reported indigenous to the United States. Both these forms are mainly 

 confined to southern Florida, having a far more restricted range than the palmet- 

 toes ; and although both, when transplanted, thrive along the northern shores of the 

 Gulf of Mexico, they are evidently subject to being driven south of this extreme 

 northern limit by exceptional rigorous winters. It also seems possible that some 

 of the Mexican species could temporarily extend into southwestern Texas, or tip 

 into the deep, warm canons of southern Arizona. 



Both the Florida Zamias are small plants of exceptional interest because of the 

 enormous size of the ovulate, and the — for cycads — numerous staminate cones borne 



by the profusely-branching 

 underground trunks. Z. 

 pumila is sparsely found in 

 the forest depths of the 

 " hummocks " or dense and 

 often lofty copses of dicotyls 

 so characteristic of the shores 

 of Floridian lakes and banks 

 of streams. Z. floridana is, 

 however, the more typical 

 species, and is often very 

 abundant in the great reaches 

 of pine woods of the southern 

 half of Florida. In its hab- 

 itat this plant thus closely 

 parallels the manner in which 

 many widely distributed 

 cycadean species of the Meso- 

 zoic grew in the open dells 

 of the great coniferous forests 

 of that age. Moreover, the 

 present cycad limit in North 

 America of course marks the 

 present line of a retreat 

 begun in the Arctic area in 

 Cretaceous time (198). 



Fig. 105. — Zamia "glabra". X iV Smooth-stemmed, low-growing branch- 

 ing cycadean trunk similar to preceding species, and like them bearing 

 notably large fronds (1.25 meters high), with large and broad pinnules. 



ZAMIA FLORIDANA. (Fii>s. 106-108.) 



As a typical form of both local and general interest Zamia floridana merits 

 further present mention. Usually, only the leafy crown is to be seen above ground. 

 It consists in from a few to twenty or more fronds of ovate or ovate-lanceolate 

 shape, but truncated, that is, evenly pinnate. The average length of the fronds is 

 about 50 cm., the petiole being 20 and the leafy portion 20 to 30 cm. long. A few 

 more or less than twenty pairs of linear pinnules are commonly present. 



