PHYLLOME AND TRICHOME. 



141 



pistil, if the dissepiments meet in the centre of the ovary, 

 thus dividing it into separate cells, the placentation is 

 central or axile ; if the ovary is one-celled and bears the 

 seeds on its walls, the placentation is parietal ; and if 

 the seeds are attached to a central column it is free 

 central. 



222. Besides the union of the ovaries there may also 

 be a union of the styles, and even of the stigmas. 



223. A very exceptional pistil is found in plants of 

 the Pine Family. Here the ovules, instead of being 



enclosed in an ovary, are 

 usually simply attached to 

 the inner surface of an open 

 carpellary leaf or scale, the 



Fig. 196. Figs. 197, 198, , ,, , , . . 



scales lormmg what is known 



as a cone (Figs. 196, 197, and 198). The plants of this 

 family are hence called gymnospermous, or naked-seeded. 



224. Nectaries. This name is given to that part of a 

 flower which has been specially formed for the secretion 

 of honey. The nectaries need not, however, be looked 

 upon as separate or independent organs. Sometimes 

 they are to be found at the base of the petals, as in 

 Buttercup j sometimes at the base of the stamens, as in 

 the Grape. Very commonly they are at the bottom of 

 deep spurs formed on one or more divisions of the 

 perianth, as in Violet, many Orchids, and in Columbine. 



225. Phyllome and Trichome. To all leaf-forms, 

 whether ordinary foliage-leaves or those special modifica- 

 tions which make up the flower sepals, petals, stamens, 



Fig. 196. -A cone. 



Fig. 197. Single scale showing position of the two seeds on the inner face. 



Fig. 198. One of the winged seeds removed. 



