6 SUPPLEMENT. 



Gnetums are woody vines or lianas; Ephedra consists of erect shrnbs 

 with green or yellowish articulated branches quite destitute of leaves, 

 while the peculiar Tumboa has a short trunk only a foot hioh, but 

 several feet in diameter, from which depend two long strap-shaped 

 leaves of so tirm a texture that they endure for many years. The 

 (jnetales possess no economic and little ornamental value. The young 

 heritage and the berry-like fruit of (nufnm (rjhnnov is said to be eaten 

 as a vegetable in India. 



ORD?m CYCADALES. (FiG. 3.) 



This order, like the last, is restricted to a single family, the Cy- 

 cadace?e or Cycad family. The group is of special interest to the 

 botanist, in view of the peculiar method by which fertilization is ef- 

 fected, mention of which has been made above. Cycads were abundant 

 in prehistoric time, as is evidenced by the large (juantities of well-pre- 

 served trunks found in the cretaceous deposits in Maryland and other 

 localities. The genera are nine in number. Of these, two are Mexi- 

 can, one Cuban, two African, one Australian, and the remainder are 

 distributed throuoh the tro])ics of both hemispheres. The o^enus C\cas 

 has a well known representative in cultivation, Ci/rdK r<'V<)l\tta of Japan, 

 It is palm-like in ap})earace, having a thick short trunk and a crown of 

 of handsome pinnate leaves of firm texture. Zamia is represented by 

 two native species in Florida, where they are known as the coontie or 

 Florida arrowroot. They are low plants, rarely exceeding a foot in 

 height, and cover large tracts in the dry barrens. The leaves are not 

 unlike those of a coarse brake or fern, and the thick erect, mostly sub- 

 terranean stems abound in starchy matter from which a very good 

 ijrade of arrowroot is obtained. 



The inflorescence of Cycads is dioecious, like that of the Gnetads. 

 The male and female flowers are produced separatel}' in dense cones, and 

 consist merely of anthers and ovules without any perianth, borne on 

 thick scales. The seeds are either hard or with spongy outer cover- 

 ing. Although our cultivated cycads and the native species of Zamia 

 above referred to are dwarf plants, yet in tropical regions members of 

 this group are often tall in stature, with unbranched trunks resembling 

 those of palms, and large crowns of pinnate leaves. 



