96 MORPHOLOGY, OR COMPARATIVE ANATOMY. 



this occurs in other genera of the order, where, indeed, the four petals 

 here suppressed are generally considerably smaller. In the Larkspurs 

 (Delphinium) one petal is constantly suppressed, while the others are of 

 irregular form ; and in Aconite three out of the five petals are inconstant 

 in their occurrence, being, even when present, mere petaloid scales. 



The stamens are mostly isomerous, with either one, two, or more whorls, 

 when the floral envelopes are regular, although there are well-known 

 exceptions to this. The suppression or partial abortion of some of the 

 stamens is most common where the flowers are irregular. This sup- 

 pression is well seen in the irregular monopetalous Orders, where we find 

 curiously graduated illustrations of the phenomenon. Thus, in the Scro- 

 phulariacese, belonging to the pentamerous type, there are usually but four 

 stamens, but Verbascwn has the fifth (not always fertile) ; Penfatcmon has 

 four perfect stamens and a sterile filament ; and in Scrophularia the fifth is 

 represented by a scale in the upperside of the corolla. In Veronica three 

 are suppressed, and only two remain. In the Labiatae (fig. 166), again, 

 one stamen is ordinarily suppressed ; not unfrequently two of these appear 

 as sterile filaments ; and in Salvia, Monarda, and other genera only two 

 stamens exist. 



Either multiplication or suppression is almost the rule in the carpellary 

 circle, the isomerous condition being rather the exception. Six carpels, 

 or a double circle, occur in the 3-merous flowers of Triglochin (fig. 166) ; 

 and we have mentioned the occurrence of five carpels in the pentamerous 

 flowers of Crassula and Sedum ; in the nearly allied Saxifragaceae the 

 carpels are usually reduced to two. In Araliaceae, Aralia has five car- 

 pels, different species of Panax three and two, while in the allied order 



Fig. 166. Fig. 167. 



Fig. 166. 3-merous flower of Triplochin maritimum, with six carpels; x represents the bract. 

 Fig. 167. Ground-plan of Epimedium, with 2-merous circles and a solitary carpel ; a, a are the 

 bracteoles of the pedicel. 



Umbelliferae the number 2 is universal in the carpellary circle, although 

 all the other circles remain pentamerous. In Rosacese we have almost 

 every conceivable condition ; for while multiplication takes place to a 

 great extent in Rosa, Frar/aria, and allied genera, the normal five carpels 

 occur in Spircea and the Pomaceous suborder ; in Ayrimonia the number 

 is reduced to two ; Sanyuisorba has two or one ; while in the Drupaceous 

 suborder, in Primus &c., only one carpel regularly exists, a condition 

 which is the rule throughout the related extensive pentamerous order 

 Leguminosse. In Ranunculaceae the number of carpels varies much. In 

 Berberideae the outer circles are 2-merous and the carpel is solitary 

 (fig. 167). Suppression of a portion of the carpels is almost constantly 



