CHAPTER XXIII 



THE CONIFERS 



ALL seed-plants, with the exception of certain fossil forms 

 (e.g. Pteridosperms and some fossil Clubmosses), are grouped as 

 Phanerogamia, the fourth and highest class of the Vegetable 

 Kingdom. The further subdivision of this class into Gymno- 

 sperms and Angiosperms is based on the manner in which the 

 ovules are borne ; those of the former are freely exposed, as in 

 the Cycads already considered, whilst those of the latter, the 

 Flowering Plants proper, are enclosed in a structure called the 

 ovary. There are, however, several other points of contrast, 

 which will become apparent later. The Phanerogams as a whole 

 are further distinguished by a higher differentiation of the strobili 

 than is found among Pteridophyta. 



The Gymnosperms include, apart from the Cycads, the Maiden- 

 hair Tree (Ginkgo biloba, cf. p. 326), the important group of the 

 Conifers, and other forms known only as fossils. The Conifers, to 

 which belong such familiar plants as the Scotch Fir (Pinus sylvestris, 

 Fig. 200), Larch (Larix europcea, Fig. 193), Yew (Taxus baccata, 

 Fig. 201), etc., are essentially characteristic of temperate zones, 

 some being the chief forest trees of colder regions (cf. p. 391). 

 They furnish some of the most important sources of timber 

 (p. 129), turpentine, resin, etc. (p. 63). There are some 350 known 

 species, of which more than a fifth belong to the genus Pinus. 



All the Conifers are woody, and the majority are trees. The 



regular habit, so marked in the Spruce Fir (Picea excelsa) and 



Cypress (Cupressus), characterises the group and is an outcome of 



the monopodial branching. 1 The feature which gives them their 



most distinctive stamp, however, is the foliage, which in general 



consists of small needle-like leaves (Figs. 192, 193, and 201). 



1 Cf.F. &S., p. 75. 



334 



