130 MORPHOLOGY, OR COMPARATIVE ANATOMY. 



where the receptacle is flat the carpels are in whorls; but if the 

 receptacle is elongated the carpels are arranged spirally, as in 

 Magnolia. 



Syncarpous Pistil. Where, as very frequently happens, the 

 carpels cohere together, as the stamens do in the condition called 

 monadelphous, a syncarpous or compound pistil is formed ; and as 

 the carpels occupy the apex of the receptacle, they do not form an 

 open organ, like the tube of filaments in Malva for example, but 

 a closed case, appearing externally like a solid body, mostly with 

 ridges and grooves on the outside, indicating its compound nature. 



The union varies very much in degree ; even in multiple pistils we find 

 the carpels sometimes cohering strongly while young, and separated only 

 as the seeds ripen ; and in true compound pistils the union does not 

 always extend to the summit of the ovarian region, as we observe in the 

 Saxifragaceae, where the apices of the ovaries diverge. More frequently 

 the ovarian regions are firmly coherent ; and then the styles may be 

 wholly free Pink, Silene (fig. 173), Hypericum, &c. ; or united part of 

 the way up, as in some Malvaceae (fig. 247) ; or entirely, but with the 

 stigmas distinct, as in Geranium, &c. ; or the stigmas may also be con- 

 fluent (Primulaceae, Solanacese, &c.). Sometimes, however, the styles or 

 stigmas exhibit the reverse condition, and are split into two parts, as in 

 the styles of Drosera, Euphorbia, &c. 



Adhesion. The conditions arising from adhesion or want of se- 

 paration have been referred to already, under the names of superior 

 or inferior calyx or ovary. The condition depends on this circum- 

 stance whether the vascular bundles for the carpellary whorl are 

 detached at once from the axis, or whether they are held together 

 by a sheath of cellular tissue for a time before becoming detached. 

 They are always associated with cohesion when more than one 

 carpel exists. 



The styles, when the ovary is inferior, are either coherent, as in 

 Iridaceae (fig. 260), or distinct, as in the Umbelliferae (fig. 172) and Rubia- 

 ceae. In Saxifraga (fig. 171), and in some other cases, the ovary is half- 

 inferior. When the stamens are consolidated with the pistil, the gynan- 

 drous condition is produced. In Orchidaceae the filaments are inseparable 

 from the style, forming a column surmounting the ovary; in Asclepia- 

 daceae the anthers adhere to the summit of the free compound style ; in 

 AristolochiaceaB the filaments apparently adhere to the base of the com- 

 pound style (fig. 242). (See under Aristolochiacese.) 



Compound pistils are sometimes smooth and even on the out- 

 side, showing no sign of their compound nature, as in Primula, 

 &c. ; in other cases they exhibit more or less deep furrows at the 

 lines of junction, sometimes dividing them into lobes. But the 

 internal structure of the ovary generally indicates the number of 

 carpels entering into its composition very plainly. 



