172 THE CULTIVATED EVERGREENS 



planation for the sequence of the genera as adopted. As these 

 keys are of use only if flowers or fruits are available, another 

 key to the genera of all three families combined and based on 

 vegetative characters only is given below. This should make it 

 possible to determine any coniferous plant even without flowers 

 or fruits. There may be, however, some cases in which the key 

 may fail, particularly if only young seedling plants are avail- 

 able, since in many conifers, chiefly in the Cupressineae and Taxo- 

 dinese, the foliage in its juvenile stage is very different from that 

 of the adult, as may be seen if Chamceq/paris pisifera and C. 

 pisifera var. squarrosa are compared; even the arrangement 

 of the leaves may change, as in Widdringtonia Whytei which 

 has alternate leaves in its juvenile stage and opposite in the 

 mature plant; also some other abnormal garden forms show a 

 great deviation from their type. Furthermore, some species and 

 even a few genera show such a great resemblance in their 

 vegetative characters, though different enough in flowers and 

 fruits, that it is almost or quite impossible to give an accurate 

 description of these differences which, however, may usually be 

 perceived if the plant in question can be compared with cor- 

 rectly named specimens or plants. 



KEY TO THE GENERA OF CONIFEROUS PLANTS 

 BASED ON VEGETATIVE CHARACTERS 

 A. Plants with evergreen foliage. 



B. Leaves alternate, scattered or clustered, 

 c. Arrangement of leaves scattered. 



D. Form of leaves linear, lanceolate, or subulate, rarely 

 oblong to elliptic. 

 E. Winter-buds not scaly or with green or greenish 

 scales: leaves decurrent into a green leaf- 

 cushion, not articulate at base. 

 F. AU the leaves flattened, linear or linear- 

 lanceolate to oblong-ovate. 

 G. Leaf broad, obtuse, generally oblong, leaves 

 occasionally opposite. (See also Phyllo- 

 cladus, p.l81, with broad, lobed, or toothed 

 leaf-like cladodia) Agathis, 245 



