368 PART IV. — VEGETABLE TAXONOMY. 



filbert before fertilization. The embryos are usually dicotyle- 

 donous, and the cotyledons do not escape from the seed-coats 

 during germination. 



The female flowers of the species of Cycas differ from those of 

 other members of the order, in the fact that the ovule-bearing 

 leaves form a rosette, composed of leaves similar in shape but 

 smaller in size than the ordinary foliage ones, and the ovules take 

 the place of the ordinary pinnae. See Fig. 569, A. Moreover, the 

 axis that bears the floral leaves does not stop growing, but is 

 continued upward through the flower and bears above the latter 

 both scale-like and ordinary leaves. 



Cycas revoluta is commonly cultivated in hot-houses, and one 

 species, Zamia integrifolia, commonly called the Coontie, is 

 native to the United States, growing in southern Florida. 



(B) The Coniferae constitute by far the largest and most 

 important order of the class. It includes the Pines, Yews, 

 Cypresses, Firs, Larches, Junipers, Araucarias, etc. A few of the 

 species are shrubs, but most are trees of medium or large size ; 

 the stems are very commonly excurrent or spire-shaped ; branch- 

 ing occurs freely, and the branches spring from the leaf-axils, 

 but not all, or even the larger proportion of the axils, produce 

 buds ; the leaves are, with few exceptions, unbranching, simple- 

 veined and of small size, and are commonly very abundant, in 

 some instances, as in the Arbor Vitaa and Red Cedar, so thickly 

 clothing the branches that the branch itself is completely obscured. 

 Many of the species produce, besides the foliage leaves, brown 

 scales, which mainly serve a protective purpose, as bud-scales, 

 etc., as in the Spruces ; but in one Australian genus, Phyllo- 

 cladus, no green leaves are developed, but leaf-like branches 

 springing from the axils of scales, take their place. 



In their internal structure and mode of growth, the stems 

 very closely resemble those of Dicotyledons, the most important 

 difference being the fact that the elements of the secondary wood 

 consist almost entirely of discigerous trachieds. (See Vegetable 

 Histology). 



Nearly all the species produce terebinthinous secretions, and 

 many valuable resinous and oleo-resinous products are obtained 

 from the order. 



The flowers are, in some species, monoecious, in others 



