1202 A TEXTBOOK OF THEORETICAL BOTANY 



THE GYNOECIUM AND CARPELS 



The term gyncecium is applied to that portion of the flower which is 

 composed of the carpels collectively or, in a minority of flowers, of one 

 carpel alone, in which latter case the two terms are synonymous. The old 

 term pistil was dropped because it had been applied w'ithout discrimination, 

 both to the individual carpels, when they were free from one another, and 

 to the compound structure formed by the fusion of several carpels. 



The carpellary group is generally quite clearly delimited and occupies 

 the morphologically uppermost part of the floral receptacle, whose restricted 

 growth places the gynoecium usually in the centre of the flower. A distri- 

 buted gynoecium rarely occurs, although in some members of the Moni- 

 miaceae, where the receptacle is concave, the carpels in female flowers may 

 occur all over its hollow surface. 



We have previously dealt with the variations of form in the receptacle 

 which affect the position of the gynoecium in relation to the other organs of 

 the flower, which may be either hypogynous, perigynous or epigynous. 

 We shall return briefly later on to the interpretation of the inferior ovary, 

 which has a bearing on the evolution of the flower as a whole. 



As to the term carpel itself, we apply it to a unit structure, bearing and 

 usually enclosing an ovule or ovules, and normally composed of three parts: 

 an ovary, which is a hollow structure whose wall surrounds the ovules; a 

 style, which is a column of tissue arising from the ovary; and a stigma, 

 which is a receptive, glandular pad of tissue surmounting the style. The 

 first and last of these are the essential parts, the presence of which consti- 

 tutes the condition of angiospermy. The style is a convenience which aids 

 pollination in many flowers but which is sometimes absent (Fig. 1173). 



The whole gynoecium is sometimes carried upwards by the exceptional 

 elongation of an internode of the floral axis, known as a gynophore, w^hich 

 may sometimes reach an extraordinary length, as in the Capparidaceae, 

 raising the gynoecium completely above the flower. Similarly, individual 

 carpels, which are generally sessile on the receptacle, may be severally 

 elevated on pedicels, as in Eranthis, Thalictnnn, ZannichelUa and many other 

 genera. 



When all the unit carpels are separate the gynoecium is called apocar- 

 pous, and if they are coherent, syncarpous or, more correctly, coenocar- 

 pous. Cohesion occurs in all degrees of completeness. It may be no more 

 than cohesion of the ovaries at their bases, as in Labiatae, or the ovaries may 

 be united while the styles remain free as in Caryophyllaceae, or there may be 

 a union of all parts except the stigmas, e.g., Scrophulariaceae, or finally a 

 complete union, as in Cruciferae and many other families. In coenocarpous 

 flowers the ovary formed by the union of several carpels is called a com- 

 pound ovary (Fig. 1174). It may be divided by septa internally into a 

 number of loculi, or spaces, corresponding to the number of carpels 

 involved, but in the most complete unions the dividing septa are absent 

 and the compound ovary becomes unilocular, showing only traces of its 



