CONIFER*. 259 



cortex), partly in intercellular glands or passages (both in the 

 cortex and wood). Taxus is the only genus which has no resin. 



There are about 350 species, mostly from the Northern Temperate zone 

 (especially North America and Siberia), where they grow gregariously and form 

 the most northern forests. The Juniper, Scotch Fir, and Yew are natives of 

 Great Britain. 



This class may be divided into two families : 



1. Taxoideae. The ovules have either one integument, the 

 external part of which is fleshy, and the internal hard and stone- 

 like ; or two integuments, of which the external is the fleshy and 

 coloured "aril." "Ovuliferous scales" are wanting. The cones 

 are never woody, but are generally sacculent, the bracts become 

 fleshy, or cones usually are not developed. The seeds project more 

 or less freely beyond the bracts. 



2. Pinoideae. The ovules have two integuments, the external 

 one of which is leaf-like and becomes developed as the " ovuli- 

 ferous scale " ; if there are several of these in each flower they 

 unite and form a " symphyllodium." This may remain free or 

 unite with the bract. The cones are most frequently woody, 

 rarely succulent. The seeds are hidden among the cone-scales. 



Family 1. Taxoideae. 



This family, considered to be most nearly related to the Cycadeee, 

 also made its appearance at a very early period. There is only 

 one order. [See note on page 272.] 



Order. Taxaceae. The characters have been given above. 



A. CEPHALOTAXEJ: is the oldest group, presumably the connect- 

 ing link between the Cycadeae and the other Coniferaa. The flower 

 consists normally of two ovules. Aril wanting. One integument. 

 Seeds drupaceous. The flowers in Ginkgo biloba (Salisburia} 

 are situated in the axil of foliage- or scale-leaves. The stamens 

 bear only two pollen-sacs (Fig. 260 A). The female flower has 

 two ovules, placed together at the end of a long, bare axis (Fig. 

 260 (7) . Round the base of the ovule a small collar (ar, in Fig. 

 260 D) is found, which may probably be considered homologous 

 with the collar-like outgrowth which surrounds the base of the 

 Cycas- ovule. The seed resembles a Plum, and has a fleshy external 

 coat, surrounding a hard internal layer. The embryo is developed 

 after the seed has fallen off. The Ginkgo- tree has long-stalked, 

 fan- shaped leaves, more or less indented, with dichotomous veins 



