THE COMMENCEMENT OF THE PHANEROGAMIC FRUIT. 



77 



three receptaeular ridges. The ovules are borne on longitudinally-running cushions 

 on the carpels. This class of ovary is found in great variety amongst the 

 Orchidaceas (figs. 207 ^ and 207 \ and figs. 212 1.^. s.*). 



Carpels of Two Kinds. 



(14) One series of carpels, destitute of ovules, arise from the margin of the 

 dccply-excavated receptacle, roofing it in. Another series, metamorphoseid into 



Fig. 209.— .Structure of Phanerogamic Ovaries. 



1 Longitudinal section of tlie ovary of Cereus grandijtorus. " Ovules on a branched placenta from the base of the ovary of 

 Cereiis. 8 Longitudinal section of the ovary of Uedychium angusti/oUuin. * Deliisced fruit of the same plant. 6 Trans- 

 verse section of the ovary of the same. « Longitudinal section of an Almond t[v\ver (Aviygdalui coitununis). 7 Longi- 

 tudinal Bection of the ovary of the same. ^, 9 Transverse and longitudinal sections of the ovary of the Willow-herb 

 (Epilobium angustifoliim). i natural size ; ^ *, *, "^ slightly magnified; 2,7^8^9x10. 



ovule-bearing strings, arise spirally from the inner wall of the receptacle and 

 project into the ovarian cavity. Examples are aflforded by the Cactacese, e.g. 

 Opuntia and Cereus (figs. 209 ^ and 209 ^). 



(15) One series of carpels closes the mouth of the excavated receptacle, as in 

 (14). The other series, bearing the ovules, are filamentous, and arise as a whorl 

 from the base of the receptacle; they are consolidated with a thread-like prolonga- 

 tion of the tip of the axis which runs up as a central column. Example: — The 

 Willow-herb {Epilobium, figs. 209 « and 209 9). 



