SEED. 



105 



close to shelter tlie seeds, but protect them by closely overlapping each other until 

 ripe. They are sometimes woody, when they form either a conical spike {Pine, fig. 

 674), or a globular head {Cypress, fig. 575) ; when fleshy and connate, they simulate 

 a drupe {Juniper, fig. 576). 



577. Feaseed (mag.), deprived of 

 half its integument and one of 

 its cotyledons. 



SEED. 



The seed {semen) of phsenogams is the ovule when fertilized, ripe, and ready for 



germination ; it contains the embryo {emhryo, plantula, corculum), which is destined 



to reproduce the mother-plant. Let us recapitulate the structure of the embryo in 



the Pea (fig. 577). It is composed of a caulicle {caulicuhis, 



t), a radicle {radicula, e), two cotyledons {cotyledones, c), and 



a plum,ule {gemmula, plumula) ; it is enveloped by a double 



integument, of which the outer (i), or testa {testa), is 



attached to the hilum {hilus, umbilicus) by the funicle 



{funiculus, f), which rises from the placenta {placenta, p) ; 



and the inner (e), or endopleure,^ {endopleura) provides a 



passage for the nourishing juices by the chalasa {chalaza, h), 



which communicates with the hilum by means of a cord (a), 



the raphe {raphe). Near the hUum is a small opening (m), 



the micropyle {micropyle), by which the ovule is fertilized by 



the pollen. As a general rule, the radicular end of the embryo answers to the 



micropyle, and the cotyledonary end to the chalaza ; the exceptions to this rule, 



which are rare, and do not invalidate it, will be specified. 



Relative Positions of Seed and Embryo. — It is important to observe that, in the 



early condition of the ovule, the hilum and chalaza are united ; consequently the 



raphe does not exist, and the micropyle occupies the opposite, or free end of the 



ovule; also that 1, the base of the fruit (ovary ^), is the point by which this is 



attached to the receptacle, and its top is the point from which the style springs ; 

 2, the base of the seed is the point by which it is attached to the 

 funicle or placenta, and which is indicated by the hilum ; the 

 top of the seed is the extremity of an imaginary straight or 

 curved line drawn through the axis of the seed. The axis of the 

 ovary is defined in the same manner. 

 The embryo has also its axis; its 

 base is its radicular, and its top its 

 cotyledonary extremity. 



The top of the seed is obvious 



r^i^£riS°^^a™trtbe whenever the hilum occupies either 



i^Sl:^T''l^'rtl extremity of the long axis of the seed, 



^Tri.Iiaf^d^,l7^B as is usually the case {Nettle, fig. 



the top of the ovary. 578 ; /Sa^e, fig, 579; Chicory, 580) ; 



but sometimes the hilum is placed at the middle of the long axis of the seed 



■ Sometimes called tegmen.-BT>. seed in relation to the ovary, where we should say 



2 Throughout this section the authors speak of the carpel or fruit.— Ed. 



678. Nettle. 

 Achene cut vertically (mag.), 

 showing one of the _ large 



&r 



579. Sage. 



Achene cut vertically 



(mag.), ov, ovary ; 



Gr, seed. 



