PINES (PINACEAE) 



451 



maining portion of the nucellus hardens, so that the seed when 

 mature resembles some of the stone fruits, such as the Plum, 

 although it is a seed and not a fruit. 



It is obvious that a seed is simply a transformed megaspo- 

 rangium. In the Cycads a seed is a megasporangium which has 

 its outer portions modified for protection and contains within 

 a female gametophyte bearing a _ 

 young sporophyte. Thus the re- 

 duction of the female gametophyte 

 through the Pteridophytes and 

 finally its retention in the mega- 

 sporangium in the Cycads so that 

 the young sporophyte also develops 

 within the megasporangium were 

 important steps in the evolution of 

 the seed. 



f ^Although the Cycads resemble 

 Ferns in having swimming sperms, 

 and in having leaves and stems that 

 are Fern-like, they contrast with 

 them in such new features as differ- 

 entiation of strobili, simpler ga- 

 metophytes, pollination, growth of 

 pollen tubes, and the seed. 



Pines (Pinaceae) 



The Pines are a subdivision of the 

 Pine family (Pinaceae} . In addition 

 to the Pines, the Pine family in- 

 cludes the Spruces, Firs, Hemlocks, 

 Larches, Cedars, Redwood, Cypress, 

 and others. The Pine family is an 

 exceedingly important one because it includes a large proportion 

 of the trees from which lumber is obtained. The Pine family 

 belongs to the order of Conifers (Conifer ales}, so named because 

 of the cones which they bear. Not all of them, however, bear 

 dry cones like the Pines, for some have fleshy fruit-like structures, 

 as the berry-like structures of the Junipers illustrate. All of the 

 representatives of the Pine family are interesting, but a study of 

 their life history will be limited to that of the Pine, 



FIG. 400. Pine sporophytes. 

 After Miss Hay den. 



