THE OVULE. 



297 



short branch, and surrounded by a fcw small bracts. As the ovules 

 are here naked and exposed to the direct contact of the pollen, and 

 the seeds are not enclosed in anything answering to a pod, these 

 have received the name of GymkoSI'KRMOUS Plants, that is, plants 

 with naked seeds. 



Sect. VIII. The Ovule. 



561. Ovules (420, 543) are bodies borne by the pistil, which, on 

 being fertilized and having an embryo developed in them, become 

 seeds. To their formation, fertilization, and protection all the other 

 parts of the blossom are subservient. They vary greatly in num- 

 ber, from one (solitary) in each carpel or cell to a multitude. When 

 few and uniform in number, they are said to be definite ; when too 

 numerous to be readily counted, indefinite. 



5G2. As to situation and direction, they are erect when they arise 

 from the very bottom of the cell (Fig. 518) ; ascending, when fixed 

 above its base and rising obliquely 

 upwards (Fig. 517) ; horizontal, 

 when they project from the side of 

 the cell, without turning either up- 

 wards or downwards (Fig. 342) ; 

 pendulous, when they hang or turn 

 obliquely downwards (Fig. 387) ; 

 and suspended when hanging perpendicularly from the very summit 

 of the cell (Fig. 519). These terms apply to the seed as well as to 

 the ovule. 



5G3. An ovule is at first a minute projection of the placenta (Fig. 

 530), of soft and homogeneous parenchyma; but it soon acquires a 

 definite form and structure. It may be either sessile, or raised on a 

 stalk, the Funiculus, Podosperm, or seed-stalk. The point of 

 attachment, which in the seed forms the scar, is called the Hilum. 



564. It consists of a kernel or nucleus, and usually of one or two 

 coats. The nucleus is the essential part of the organ ; in it the 

 embryo is formed, and the coats become the integuments of the 

 seed. The ovule of the Mistletoe consists of a naked nucleus only, 

 there being no integument. The ovule of the Walnut has oidy one 



FIG. 517. Ovary of a Buttercup, divided lengthwise, to display its ascending ovule 618. 

 Some of Buckwheat, with an erect o\ u!e. 013 Same of Anemone, v.itli a su-pcuded ovule. 



