74 



PBOPAGATIOK OF PLANTS. 



in the Chestnut, Filbert and Walnut, the outer husk 

 enclosing the nut becoming detached at maturity from 

 the parent plant, as well as from the nut proper, while 

 within the latter there is another integument in the form 

 of a thin membrane surrounding the kernel. In some 



of the Oaks the outer husk is 

 but a shallow cup, figures 31 

 and 33 ; in other species the 

 cup extends farther up or is 

 deeper, figures 33 and 34, 

 while in a few the nut is nearly 

 covered with the husk. 

 The stalk of the seed is called the funiculus, and 

 when a seed breaks loose from the stalk at maturity it 

 leaves a scar, as seen in the garden bean, which is called 

 the Mlum. Sometimes this funiculus is extended or 

 even rolled up within the seed-vessel, forming a thread- 

 like attachment to the seed, as seen in those of the Mag- 

 nolias, allowing the seed to drop out and remain for a 



Kg. 31— (J. ALBA. 



Fig. 35. — ^ULMUS SUBEEOSA. 



Fig. 36. 



U. CAMPESTEIS. 



time suspended to the seed-vessel. On the seed of the 

 Common Swamp Magnolia {Magnolia glauca), this um- 

 bilical cord is an inch or more in length, and quite con- 

 spicuous as the seed drops out of the cone-shaped pods 

 in autumn. 



In form, size and structure, as well as in chemical 

 composition of seeds, variation is the rule, as well as in 

 other parts and appendages of plants. Seeds of differ- 



