72 THE STRUCTURE OF FLOWERS. 



wtich has proved to be misleading. Thus, in Geranium and 

 allied genera, the beak-like process from which portions of 

 the carpels separate when ripe is not axial at all, but simply 

 the coherent placentas of an entirely carpellary origin."^' 

 This will be understood from the description I have given of 

 Pelargonium (p. 65). 



The raericarps of the fruit of an umbellifer are also 

 supported on a carpophore, which is likewise usually described 

 as axial ; but anatomical investigations do not warrant the 

 conclusion. The commissural surfaces are obviously merely 

 the result of rupture between the two carpels which have 

 cohered ; and, in consequence of this union, each epidermis 

 fails to develop its true character, but remains in an arrested 

 condition, having the cells somewhat smaller than the rest 

 of the ground tissue. This enables the mericarps to separate 

 readily on maturity. A double fibro-vascular cord runs up 

 the centre to supply ovular cords at the summit of the 

 ovary-cells. If one traces the cords from the pedicel, there 

 will be found in the latter a complete fibro-vascular cylinder. 

 This spreads out at the base of the inferior ovary into ten 

 clearly defined cords which run parallel to each other from 

 base to apex, to furnish the petals and stamens ; while two 

 only coalesce and form the axial cord. It is this cord which 

 constitutes the stylopod when the fruit is ripe. Hence it 

 is not axial, but simply the combined marginal cords of the 

 two ovary-cells. 



Free Central Placentas.— The position of an ovule or 

 ovules on a central support, free from the wall of the ovary, 

 or directly on the base of the chamber, and apparently quite 



* Prof. A. Gray (I.e., p. 213) and Henfrey (El Course of Bot., 4tli ed. 

 p. 100) both speak of it as axial ; though it was quite correctly described 

 and figured by M. Seringe so long ago as 1838 (Mem. sur la Fruit des 

 Geraniacdes) : *' Les bords do chaque carpel placentaires sont restes et 

 forment la colonne." 



