30 INTRODUCTION. 



the edges of which the seeds are alternately attached. When the 

 Pod is as broad as long, it is called a Pouch or Silicula, as in 

 Fig. 139. 



3. The Legume (Fig. 140.) is a dry elongated seed-vessel, 

 formed of two oblong valves, without any longitudinal partition, 

 and bearing the seeds along one of its margins only. 



4. The Nut (Fig. 141.) is a seed covered with a hard peri- 

 carp or thell which does not burst. The seed is called the kernel. 



5. The Drupe (Fig. 142.) is a seed, covered with a hard endo- 

 carp, a fleshy mesocarp, and a membranous epicarp. 



6. The Apple (Fig. 143.) is a fleshy fruit, containing a capsule, 

 or rather it is an enlarged fleshy calyx inclosing a membranous 

 or cartilaginous pericarp, divided into several cavities, containing 

 one or more seeds. 



7. The Berry (Fig. 144.) is a juicy fruit, which contains se- 

 veral seeds, and never bursts. The Compound Berry (Fig. 145.) 

 consists of several single ones, each containing a seed. 



The Cone or Strobilus (Fig. 146, 147.) is a catkin hardened 

 and enlarged. 



VII. Of the Seed. 



The Seed is the part of the plant which is destined for its 

 propagation. It often consists of two halves, called cotyledons 

 (Fig. 148.), which at germination change into leaves. Between 

 these, on one side, is the Embryo (Fig. 148, a.), consisting of 

 two bodies, one which descends into the earth, becoming a root, 

 and is called the Radicle (Fig. 143, b.), the other, or Caulicle, 

 ascending and becoming the stem and leaves. (Fig. 148, c.) The 

 cotyledons are covered with an outer and an inner coat. The 

 depression seen externally opposite the place where the embryo 

 lies, is called the scar. The seed while growing is attached to the 

 parent plant by a thread called the umbilical cord. 



But many seeds have only one cotyledon, which envelopes the 

 embryo ; and others have no cotyledon at all. Hence an arrange- 

 ment of plants into Acotyledonous, Monocotyledonous, Dicotyle- 

 donous, or having no cotyledon, one cotyledon, or two cotyledons. 



Seeds are very diversified as to form, but it is only necessary 

 here to describe certain parts which are frequently attached to them. 



The Pappus or Seed-down is a kind of bristly or feathery 

 crown attached to certain seeds or rather fruits. It is 



Simple (Fig. 149.), when it consists of undivided hairs. 



Feathery (Fig. 151.), when each of the hairs is subdivided 

 like the shaft of a feather. 



