3o6 CLASSIFICATION 



Division 2. Gymnospermia 



The Gymnospermia form a smaller group of plants 

 than the parallel group of Angiospermia, hence it is 

 not necessary to split up this Division of plants into 

 intermediate Glasses and Sub-classes, as is necessary 

 in Angiosperm,ia. 



Gharacters of the structure of Gymnospermia as 

 compared with Dicotyledons. — Flowers achlamydeous 

 — unisexual, monoecious or dioecious, anemophilous. 

 Garpels open, pollen falls directly on to the ovule. 

 Structure of stems and roots similar to that of Di- 

 cotyledons, but the vessels are replaced by tracheids, 

 the bordered pits very prominent, and there are resin 

 ducts both in the cortex and the wood. It is at once 

 divided into three Natural Orders, namely, the Cyco' 

 dacece, the Coniferce, and the Gnetacece. 



Nat. Order i. Cycadacece. — Stem usually un- 

 branched and thick, like the stems of Palms. The 

 primary root is a tap-root, as in Dicotyledons. Leaves 

 are closely crowded upon the stem, and of two kinds, 

 namely, large, stiff, sometimes spiny, pinnate or 

 pinnifid, green foliage leaves, and small, dry, brown 

 scale-leaves, with a felt-like mass of brown hairs. 

 In the genus Cycas (fig. 276) the pinnate leaves 

 form a handsome palm-like crown at the top of the 

 stem. The two kinds of leaves alternate with each 

 other in successive zones of the stem. In Cycas, the 

 pinnce or leaflets when young are circinately folded, 

 as in Ferns, but the leaf as a whole grows straight 

 forward. In the genus Zamia the leaf itself is cir- 

 cinately folded, while the pinnae or leaflets are straight. 

 The crown of foliage leaves is renewed at intervals of 

 one or two years, but the scales and the bases of the 

 leaf-stalk persist on the stem. The flowers are always 



