ESSENTIAL ORGANS. THE OVULE. 



229 



erect, as in Polygonacea? and Composite (fig. 423); or it may be inserted a 

 little above the base, on a parietal placenta, with the apex upwards (fig. 

 424), and then is called ascending, as in Parietaria. It may hang from 

 an apicilar placenta at the summit of the ovary, the apex being down- 



wards, and be inverted or pendulous, as in Hippuris vulgaris (fig. 425), 

 or from a parietal placenta near the summit, and be suspended, as in 

 Daphne Mezereum (fig. 426), Polygalacea?, and EuphorbiaceaB. Some- 

 times a long funiculus arises from a basal placenta, reaches the sum- 

 mit of the ovary, and suspends the ovule, as in Armeria; at other 

 times the hilum or true organic base appears to be in the middle, and 

 the ovule becomes horizontal, peltate (pelta, a shield), or peritropom 

 (vipl, around, and Tpevu, I turn). All these modifications are influenced 

 by the relative position of the hilum and foramen, the length of the 

 funiculus, and its adhesion, as well 

 as the position of the placenta. 



472. When there are two ovules 

 in the same cell, they may be 

 either collateral, that is, placed side 

 by side (fig. 427), or the one may 

 be erect and the other inverted, 

 as in some species of Spiraea and 

 vEsculus (fig. 428), or they may be 

 placed one above another, each 

 folloAving the same direction. Such is also the case with ovaries con- 

 Fig. 423 426. Carpels belonging to different flowers, cut vertically to show the different 

 directions of the solitary ovule, o, contained in them. /, Funiculus. r, Raphe. c, Chalaza. 

 .1, Base of the style. 



Fig. 423. Carpel of Senecio vulgaris, with a straight or erect anatropous ovule. 



Fie. 424. Carpel of Parietaria officinalis, pellitorv, with an ascending orthotropous ovule. 



Fig. 425. Carpel of Hippuris vulgaris, Mare's-tail, with a reversed or pendulous anatropous 

 ovule. 



Fig. 426. Carpel of Daphne Mezereum, with a suspended anatropous ovule. 



Fig. 427. Carpel of Nuttallia cerasoides, with two suspended collateral ovules, o, One of the 

 ovules. /, Funiculus. s, The base of the style. 



Fig. 428. One of the loculaments of the ovary of ^Esculus hybrida, laid open to show two 

 ovules, o o, inserted at the same height, but turned in different directions, m m, Micropyle in- 

 dicating their apex s, Base of the style. 



