68 



PROPAGATION OP PLANTS. 



Pine (P. Stroius), figure 17. The cotyledons, however, 

 give no indications of the number or arrangement of the 

 true leaves, which appear later on the plant, for in the 

 One-leaved Pine there are from seven to ten cotyledons, 

 while the seeds of Sabine's Pine produce fifteen to sixteen, 

 and later the true leaves are arranged with only three in 

 a sheath or bundle. 

 Another dicotyledonous character is wanting in the 



leaves of a large 



majority of the coni- 

 fers, and that is the 



branching veins, for, 



with only a few ex- 

 ceptions, their leaves 



are long, slender and 



with parallel veins ; 



consequently, in 



seeking characters to 



aid us in separating 



the dicotyledonous 



from the monocoty- 



ledonous plants, we 



must not expect to 



find all equally well 



developed, or even 

 always foremost in any one genus or 

 family. For instance, the common garden 

 Pea has two distinct and readily separated 

 cotyledons and its leaves have branching 

 or netted veins, but the stalk shows no outside growth, 

 this character being confined wholly to stems that live 

 more than one season, and it is never developed until 

 the second year. The Wistaria vine is closely related to 

 the Pea, but the stem being perennial, new layers of wood 

 are annually added to the outside ; consequently, it has a 

 true exogenous stem. 



Fiff. 16. 



SEEDLING PINE. 



Fig. 17.— LBATBP 

 OP WHITE PINE. 



