164 SYSTEMATIC BOTANY. 



I. Cycadese. The Cycads have simple (or rarely 

 branched) stems, with large pith. They are large or small 

 trees, with the general appearance of Palms and Tree 

 Ferns. The stem is crowned with wide-spreading pinnate 

 leaves. They are all tropical or sub-tropical species (about, 

 fifty or sixty), belonging to nine genera. One genus, Zamia, 

 occurs in Florida. A kind of Sago is made from the starch 

 in the roots of some species, and in some cases the seeds 

 also are nutritious. The order originated in the Carbon- 

 iferous Age, and in the Jurassic had twenty 

 or more large genera. 



2. Coniferae. The stems of Conifers 

 (Pines, Firs, Junipers, and Yews) are 

 branched, and usually resinous. The leaves 

 are small, simple, and mostly crowded on the 

 stem (Fig. 279), but sometimes scattered ; 

 they are, in most of the species, persistent, 

 and the trees are, therefore, evergi-een. The 

 order contains thirty-three genera, and about 

 three hundred species ; about fifty of which 

 ^'^ are within the limits of the United States, 



Generally, the Conifers occur in the cooler regions of the 

 globe. Economically, the order is of great value. Most 

 of the Pines (Pinus) and Firs (Abies) furnish turpentine 

 of varying quality, secreted in resin-passages (Fig. 280, 

 r.o). Canada Balsam is obtained from the Balsam-Fir 

 (Abies balsamea) of the United States ; Venice Turpentine 

 from the European Larch (Larix Europcea) ; Damar Resin 

 from Dammara alba of the Malay Islands. The wood of 

 many species, especially that of the White Pine (Pinua 



Fig. 279. Fascicled leaves of the Pine. 



