108 CONIFERALES (RECENT) [CH. 



from complete, may afford assistance to students prepared to 

 undertake a critical study of the fragmentary records of the rocks. 



Conifers are trees or shrubs exhibiting a fairly wide range in 

 habit ; the ' great ones of the forest ' such as the Sequoias (fig. 674*), 

 the sugar Pines (Pinus Lambertiana) and Douglas Firs (Pseudotsuga 

 Douglasii) of the Rocky Mountains, Taxodium mucronatum 1 of 

 Mexico, remarkable for its enormous bulk, the tall and slender 

 Cypresses, the less formal Podocarps of the southern hemisphere, 

 the shrubby Junipers, the dwarf Dacrydium laxifolium 2 of New 

 Zealand afford examples of recent types. In most species the 

 leaves are small and crowded, not infrequently dimorphic, and in 

 Phyllodadus (fig. 675) reduced to inconspicuous and caducous 

 scales subtending phylloclades. Agathis is exceptional in having 

 narrow ovate leaves reaching a length of nearly 20 cm. (fig. 695) 

 and a similar but smaller leaf is characteristic of some species of 

 Podocarpus (fig. 676). The presence of long and short shoots is 

 a striking feature of Pinus, Larix, Pseudolarix, Cedrus, and 

 Sciadopitys : the short shoot, as Goebel says ' takes no part in 

 the construction of the permanent skeleton of the tree 3 .' The 

 whorled arrangement of leaves characteristic of several Cupres- 

 sineae and the Callitrineae is not a constant feature and, as in 

 Lycopodium, both whorled and spiral foliage may occur on the 

 same shoot. 



Conifers are monoecious or dioecious ; the microsporophylls and 

 megasporophylls are borne spirally or in whorls on separate shoots, 

 and in some genera on separate trees, except in the case of abnormal 

 bisporangiate strobili 4 . Proliferous cones are not uncommon in 

 some genera : the prolonged axis of the cone of Cryptomeria 

 japonica shown in fig. 677 bears microstrobili.in the axils of the 

 small leaves. The microstrobili are for the most part constructed 

 on a uniform plan ; they are usually short-lived, small shoots, and 

 each microsporophyll often consists of a slender axis bearing two 

 microsporangia on its lower surface and prolonged as a small 

 upturned distal expansion. In Pinus the sporangia dehisce 

 longitudinally, while Abies (fig. 684, E) affords an example of 



1 Gard. Chron. Nov. 26, 1892, p. 648. 



2 Hooker, J. D. (52) PL 815. 3 Goebel (05) p. 444. 



4 For examples see Sterzel (76); Eichler (82); Worsdell (04); Bartlett (13); 

 Shaw, W. R. (96); Robertson (06); Renner (04); Bayer (08); etc. 



