EXPLANATION OF TERMS. xxxi 



Nuts are dry, usually one-seeded fruits, and are held by such varied 

 involucres as a chestnut burr or an acorn cup. 



A Samara, or Key-Fruit, is furnished with a membranous wing. (Fig. 



49-) 



An Achene is a one-seeded fruit which does not open. 



A Capsule, or Pod, is a dry but many-seeded fruit which when ripe opens 

 in one piece and scatters its seeds. (Fig. 50.) 



A Legume is a simple pod, which when ripe, however, opens in two 

 pieces. (FiG. 51.) 



A Cone, or Strobile, is made up of a number of flat bracts which subtend 

 pistils, and so overlap each other as to form a thick spike, or head. 



Seeds, or the ripened ovules, contain within themselves the miniature and 

 rudimentary plantlet known as the Embryo. 



The Hypocotyl is the stemlet of the embryo, and from the base of which 

 grows downward the root. 



The Cotyledons, or Seed Leaves, are the first ones which a plant pro- 

 duces, and often are completely formed in the embryo. It is in accordance 

 also with the number of these first leaves that plants are termed, should 

 there be but one, Monocotyledonous ; when there are two, Dicotyledonous, 

 and Polycotyledonous when, as in the pine family, there are many seed 

 leaves. 



