282 PHYLUM XIII. STROBILOPHYTA 



mon ''White Pines" have five leaves in a fascicle, the 

 "Yellow Pines" three or two. An Arizona pine has but 

 one leaf on each twiglet. 



509. In the Cypresses (Family Ciipressaceae), and 

 Thuyas (Family Thuyopsidaccac) the woody cones are 

 small and composed of only a few scales, and the leaves 

 are small and scale-like. In the Junipers (Family Juni- 

 peraceac) some twigs bear scale-leaves and others fiat 

 leaves, while the cone scales are few and fleshy, so that 

 the cones are fleshy. In the Yews (Order Taxales) the 

 reduction in the cones is carried so far that but one scale 

 remains, and that has become fleshy. In the proper 

 Yews (Taxus) the leaves are flat, but in some related 

 genera they are scale-like. 



Laboratory Studies, (a) In the spring of the j^ear collect a 

 quantity of the microspore (staminate) cones of a pine (Scotch 

 or Austrian are very good), and preserve such as are not wanted 

 for immediate use in alcohol. Collect at the same time the 

 3'oung megaspore (ovule-bearing) cones which are to be found 

 at the ends of the new shoots. 



(6) SpUt both kinds of cones vertically, and study their 

 structure, comparing the one with the other. 



(c) Study microspores from young and mature cones. In 

 the young microspores look for the cells representing the game- 

 tophyte; in the mature microspores note the bladder-like 

 enlargements of the outer coat. 



((/) Study young megaspore cones of different ages, and note 

 the growth of the "seed scale." 



(e) Study megaspore cones one year old and note the devel- 

 opment of the gametophyte, and later the archegones. 



(/) Note that the megaspore cones of Scotch and Austrian 

 pines are two years in coming to maturity. Make vertical 

 sections of cones of various ages, and note the growth of the 

 seed. Note the thin wing (useful in their dispersion) on the 

 seeds. Make longitudinal sections of seeds, and note the 

 little sporophyte with its several leaves (cotyledons). 



(g) Examine the very young twigs as they develop in the 



