410 BOTANT. 



ous ; pith slender ; leaves small, simple, mostly crowded 

 upon the stem, sometimes scattered. 



3. Gnetacese, the Joint-Firs. Stem branched, not resin- 

 ous ; pith slender ; leaves small, opposite, upon elongated 

 internodes, or large and only two on a short, thick stem. 



Order Cycadese. — Tbe Cycads are large or small trees, with much 

 tlie general appearance of the palms and tree-ferns. They are of slow 

 growth and are long-lived ; the stem elongates by a slowly unfolding 

 terminal bud, which gives rise to a crown of widely-spreading pinnate 

 leaves, which are constantly renewed above as they die and fall away 

 below. 



ISme geiaQra.(Gyeas, Encephalartos, Maerozamia, Zamia, Ceratozamia, 

 etc.), and from fifty to sixty species, are known ; they are all tropical or 

 sub-tropical, and are about equally distiibuted in both the Eastern and 

 Western continents. Three species occur within the United States (in 

 Florida), viz., Zamia integrifo^ia, Z. pumila, Z. Floridana. 



Many species contain considerable quantities of starch in their thick 

 stems ; from this a kind of sago is made. In some cases the seeds also 

 are nutritious. 



Order Coniferse. — The Conifers are for the most part trees of a con- 

 siderable size, with branching, spreading, or spiry tops. They are 

 generally of rapid growth, and in many cases attain a great height and 

 diameter. In the greater number of species the leavt s are persistent, 

 and the trees, consequently, evergreen. 



The order contains thirty-three genera and about three hundred spe- 

 cies, which are distributed mainly in the cooler climates of the globe. 

 Fifty or more species occur within the limits of the United States. 



The disposition of the genera may be understood from the following 

 arrangement, which is essentially that of Parlatore in De Candolle's 

 " Prodromus" : 



Tribe I. Taxinece, — Flowers dioecious or rarely moncecious ; 

 fruit fleshy ; non-resinous trees or shrubs. 



Gen. Ginkgo (Salisburia), Phyllocladus, Podoca/rpus, Torreya, Taxus, 

 etc. 



The seeds of Ginkgo are eaten in Japan as a dessert. Many species 

 furnish valuable timber, which is frenerally very durable. The wood 

 of the ye-w{Taxus baccata) of Europe and Asia is almost indestructible 



Species of Podocarpua in Java, Australia, and New Zealand attain a 

 great height, and afford good timber ; allied species in the West Indies 

 and South America are equally valuable. 



Ginkgo is now planted in this country as an ornamental tree. 



Tribe II. AJbietinece. — Flowers monoecious or dioecious ; fruit a 

 woody cone (excepting in Juniperun). Resinous trees, a few shrubs. 



