GROUP V. ANGIOSPERMJE. 



467 



times it is leafy and petaloid (e.g. Iris). Monomerous ovaries have 

 but one style ; polymsrous ovaries have as many styles as there are 

 carpels, which may cohere throughout their whole length, or at 

 their lower parts only, the uppsr parts remaining distinct ; or they 

 may remain quite free, and they may even branch. The style 

 originally arises from the apex of the ovary, but it is frequently 

 displaced forwards, by the vigorous development of the dorsal 

 portion of the carpel, on to the inner side, so as to appear to be a 

 prolongation of the floral axis (gynobasic style) : this is conspicuous 

 in the Boraginacese and Labiatse, where it is surrounded by the 

 four rounded loculi of the ovary which have been already men- 

 tioned (p. 466). The style is sometimes very short, 

 and appears only as a constriction between the 

 ovary and the stigma, as in the Poppy. In some 

 rare cases it is hollow, but it is usually filled 

 with a loose tissue, called conducting tissue, 

 through which the pollen-tube can easily pene- 

 trate. 



The Stigma (Figs. 281 and 283 n) is usually 

 terminal, but it may be lateral (e.g. Iris) ; it is 

 distinguished by being covered with papillae, or 

 frequently with hairs, and by the secretion of a 

 sugary fluid which retains the pollen-grains which 

 fall upon it, and which promotes the development 

 of the pollen-tubes. The stigma is often evidently 

 distinct from the style, appearing as a lobed ex- 

 pansion ; in other cases it seems to be merely a 

 portion of the style at its end or sometimes on 

 its side. In the Poppy it is a sessile disk-shaped 

 expansion on the upper surface of the ovary ; more rarely it is 

 represented by bands of papillae on the ovary itself, when it is said 

 to be pleurogynous. 



The number of the stigmata often affords a means of ascertaining 

 whether the ovary is monomerous or polymerous ; for instance, the 

 ovary of the Compositse seems, at first sight, to be monomerous ; 

 but the two short branches of the style, each bearing a stigma, 

 show that it is dimerous. On the other hand, this character may 

 be misleading : for instance, in various Grasses the ovary bears 

 two or three stigmata, either directly, or springing from the style ; 

 hence it might be inferred that the ovary is di- or tri-merous, whilst 

 as a matter of fact it is monomerous. In this respect some few 



Fio. 283. Gj" 

 naeceum of the 

 Lily : / ovary ; g 



style; * stigma 

 (nat. size). 



