GROUP IV. GYMNOSPERM.E. 435 



1. Placental scales flat; foliage-leaves borne on both long 

 and dwarf-shoots ; branching of the stem irregular. 



(a) Leaves annually deciduous ; seed ripens In one year . Larix. 



(b) Leaves persistent ; seed ripens in two years . . . Cedrus. 



2. Placental scales thickened externally into an apophysis : 

 foliage-leaves confined to the dwarf-shoots : branches whorled. Finns. 



1. Abies, the Silver Firs. The foliage-leaves are flat, marked on the 

 under surface with two longitudinal white streaks, and show in section 

 two lateral resin-ducts: the macrosporangiate cone is developed in the 

 axil of a leaf borne on a shoot of the previous year, at some distance from 

 its apex, and when ripe falls to pieces so that the naked axis remains. To 

 this genus belongs A. pectinata (A. alba], the Silver Fir, the emarginate 

 leaves of which stand out in a comb-like manner from the branches. 



2. Picea. the Spruce Firs. The foliage-leaves are quadrangular, and 

 have two lateral resin-ducts : the macrosporangiate cone is borne 

 terminally on a shoot of the previous year, becomes pendent after 

 fertilisation, thus enabling the seeds to drop out, and then falls off entire. 

 To this genus belong P. excdsa, the Norway Spruce, the leaves of which 

 are compressed laterally. 



3. Larix, the Larches. The deciduous leaves are arranged spirally on 

 long shoots, and also in clusters on dwarf -shoots developed in the axils of 

 the leaves of the long shoots of the previous year : the microsporangiate 

 cones are borne terminally on leafless dwarf-shoots, the macrosporangiate 

 cones terminally on leafy dwarf-shoots. L. europ&a is the common 

 Larch, a native of the Alps and Carpathians. 



4. Cedrus, the Cedars. This genus differs from Larix in that the 

 leaves, which are arranged in the same way, persist for more than one 

 year, and in that the seed takes two years to ripen. The genus includes 

 three species: C. Libani, in Asia Minor; C. atlantica, in the Atlas moun- 

 tains of North Africa: C. Deodara, in the Himalayas. 



5. Pinus, the Pines. The thick placental scales are expanded at their 

 free end into a flattened rhombic surface, the apophysis : the seed takes two 

 years to ripen : the foliage- leaves persist for several years and are confined 

 to dwarf-shoots which bear cataphyllary leaves at their bases, and are 

 borne in the axils of the catapl^llary leaves of the long shoots of the same 

 year : the primary branches are arranged in false whorls near the apex of 

 the shoot of any one year, and the branches of a higher order are de- 

 veloped in the same manner : the microsporangiate cones take the place of 

 dwarf-shoots at the base of a long shoot of the same year, and are closely 

 packed : the macrosporangiate cones also occupy the place of dwarf-shoots 

 near the apex of long shoots of the same year. 



In the section Pinaster, the apophysis has a rhombic free surface with a 

 central projection (umbo) : it includes the sub-genus Pinea, characterised 

 by the fact that each dwarf-shoot bears two leaves, with about twenty 

 species, including Pinus si/lvestrli, the Scots Pine ; P. Laricio, the Black 

 Pines ; P. Pinaster, the Cluster Pine of South Europe ; P. montana, the 

 Mountain Pines of Europe; P. Pinea, the Stone Pine of the South of 

 Europe, the "seeds of which are large and edible. 



