ROSACEJJJ. 



340 



mounted by a terminal style, wliich passes through the narrow orifice 

 of the receptacle to terminate in an enlarged stigmatiferous head, 

 whose form has been compared to a bottle-brush. On one side the 

 ovary presents a longitudinal furrow externally ; here the inner 

 wall bears an ovule descending into the single cavity ; it is ana- 

 tropous, with its raphe looking towards the placenta, and the 

 micropyle superior and dorsal.' The fruit is an achene surrounded 

 by the receptacular sac, which is now thick and hard, with a wrinkled 

 surface marked by four more or less prominent ridges. Within the 

 membranous seed-coats is a fleshy exalbuminous embryo with its 

 radicle superior. Scuiguisorha officinalis is a perennial herb possessing 

 alternate imparipinnate leaves, with petiolulate leaflets, and two 

 lateral stipules adnate to the base of the petiole ; while the flowers 

 are in terminal spikes,- which are often themselves collected into 

 cymes. Each flower is axillary to a mother-bract, and possesses two 

 lateral bractlets which are normally sterile. 



Sangiiisorha and Poferiiim have been, and are still, considered to 

 form two distinct genera, because the latter have usually unisexual 

 or pol3^gamous flowers, indefinite elongated stamens, and two or 

 three carpels. When, however, we examine the numerous species of 

 Poterium described by authors, we find that they may have all their 

 flowers hermaphrodite, and 



Sanguisorha Poterium. 



that the number of carpels 

 is very variable, and may 

 be reduced to one. The 

 stamens are very numerous, 

 it is true, in P. Sanguisorha 

 (Salad Burnet, Garden Bur- 

 net— figs. 400-404) and the 

 allied species, and their 

 long filaments hang down 

 on one side in the expanded flower. But these become shorter 

 as the anthers are less developed and gradually tend towards 

 complete sterility, when they may stand erect, as in Sanguisorha. 

 At the same time the number of stamens may be reduced, so that 



Fig. 403. 

 Female flower. 



Fig. 40-i. 



Longitudinal section of 

 female flower. 



' It has only a single coat. 

 '" The flowers expand successively, not as is 

 usually the case with spikes from base to ape.\, 



but more frequently, if not constantly, from 

 above downwards, beginning cither at the tip or 

 in a zone at a variable distance from it (rtg. 3'J7). 



