rNTEODUCTIOIf. 19 



The placenta 18 the part of the inside of the ovary to which the oviiles 

 are attached, sometimes a mere point or Une on the inner sm-face, often 

 more or less thickened or raised. Placentation therefore is the indication 

 of the part of the ovary to which the ovules are attached. 



Placentas are 



ax'ile, when the ovules are attached to the axis or centre, that is : in 

 plurUocular ovaries, when they are attached to the inner angle of each cell ; 

 in unilocular simple ovaries (which have almost always an excentrical style 

 or stigma), when the ovules are attached to that side of the ovary nearest 

 to the style ; in unilocular compoi.uid ovaries, when the ovules are attached 

 to a central axis or column rising up fi-om the base of the cavity, and either 

 firee at the top, or attached also to the summit of the cavity. 



parietal, when the ovules are attached to the inner sui-face of the cavity 

 of a one-celled compound ovary. Parietal placentte are usually shghtly 

 thickened or raised hues, sometimes broad sui-faces nearly covering the inner 

 surface of the cavity, sometimes projecting far into the cavity, and consti- 

 tuting partial dissepiments, or even meeting in the centre, but without co- 

 hering there. In the latter case the distinction between the one-celled and 

 the several- celled ovary is not always very clear. 



Wlien there are but one or two ovules in each cell or in the ovary, they 

 may he pendtilojts either from the top of the ovai-y, or from a central erect 

 column, or more frequently from one side near the top ; or they may be 

 horizontally attached to one side, or erect fi-om the base. If there are two, 

 they may be moreover collateral, if placed side by side, or more rarely su- 

 perposed one above the other. 



§ 12. The Eeceptacle and relative attachment of the Floral Whorls. 



The Receptacle is the extremity of the peduncle (above the calyx), upon 

 which the corolla, stamens, and ovaiy, are inserted. It is sometimes Httle 

 more than a mere point or minute hemisphere, but it is often also more op 

 less elongated, thickened, or otherwise enlarged. 



(The term Eeceptacle is extended also to the summit of a branch or in- 

 florescence on which the flowers of a head are inserted, but we here refer 

 only to the receptacle of a distinct flower.) 



A Dish is a circular enlargement of the receptacle, usually in the form of 

 a cup (cupular), of a flat disk or quoit, or of a cushion {pulvinate). It is 

 most Irequently immediately under the ovary, within the stamens, some- 

 times between the petals and stamens, sometimes bearing the petals or sta- 

 mens, or both, at its cfrcumfei-ence, sometimes quite at the extremity of the 

 receptacle, with the ovaries arranged in a ring round it, or under it. 



The disk may be entire, or toothed, or lobed, or divided into a number 

 of parts, usually equal to or twice that of the stamens or carpels. When 

 the parts of the disk are quite distinct and short, they are often called 

 glands. 



I^ectaries are either the disk, or small defonned petals or stamens, or 

 Email appendages at the base of the petals or stamens, or any small bodies 

 ■within the flower which do not look like petals, stamens, or ovaries. They 

 were formerly supposed to supply bees with their honey, and the term is 

 frequently to be met with in the older Floras, but it is now deservedly going 

 out of use. 



When the disk bears the petals and stamens, it is frequently adherent to, 

 and apparently forms part of the tube of the calyx, or it is adherent to, and 

 apparently forms part of the outside of the ovai-y, or of both calyx-tube, 



