SPERMATOPHYTES 219 
beyond the groups previously considered in the loss of swimming 
sperms and the related structures of the ovules, and also in other 
features; nevertheless, it has also retained certain primitive features, 
as, for example, the presence of mesarch bundles in the cotyledons and 
even in the stem. The general relationships of the family will be con- 
sidered in connection with the Pinaceae. 
(b) Pinaceae 
General character. This family, characterized in general by its 
conelike ovulate strobili and dry seeds, includes the conspicuous 
FIG. 485. Transverse section of a three-year-old twig of Pinus sylvestris, showing 
the small pith, the thick and compact vascular cylinder of secondary wood, and the 
cortex; radiating lines through the wood represent the narrow pith rays; resin ducts in 
both wood (small) and cortex (large) ; to the right is a branch gap in the cylinder. 
gymnosperm vegetation of north temperate regions. Four tribes are 
recognized, as follows: 
Abietineae (9 genera and about 140 species), including pines, spruces, 
firs, hemlocks, larches, and cedars, the large genus being Pinus, with 
about 80 species. 
