ANTHOPHYTA. 



265 



the solid (woody) parts of the stems, are of a higher order 

 and far more complex than those in any other groups of 

 plants. 



Fig. 156.— Cross-seotlons of tree-trnnka. A, of a Palm : B, of an Oak, 

 Ig, woody, and ec, cortical (bark), portion ; m, pith ; rra, meaullary rays. 



Practical Studies. — [a) Make cross-sections of young stems of the 

 asparagus and hickory. Note the difference in arrangement of the 

 bundles. In like manner compare cross-sections of young stems of 

 vlrgin's-bower (Clematis) and green-brier (Smilax). 



(6) Make vertical sections of the foregoing, and note the relation 

 of the bundles to the leaves. 



(c) Make cross and longitudinal sections of the solid (woody) part 

 of a bamboo or green brier stem, and compare with similar sections 

 of oak or hickory. In the latter note the pith, medullary rays, and 

 distinct bark, not present in the former. 



{d) In the sections of oalc and hickory note the cambium-zone 

 which lies between the inner solid (woody) mass, and the outer softer 

 portion. 



502. The Angiosperms include about 100,000 species 

 and are readily separated into two sub-classes, as follows: 



Sub-Class I. Monocotyledoneae (the Monocotyledons). — 

 The first leaves produced by the embryo are alternate ; the 

 endosperm is usually large and the embryo small. 



Sub-Class II. Dicotyledonese (the Dicotyledons). — The 

 first leaves of the embryo (cotyledons) are opposite; the 



