ANGIOSPERMS. 569 



specially interesting cases will be described in Book III; it is sufficient now to 

 mention that the surface of the stigma forms the exit of the open channel of the 

 style when there is one ; if this channel is closed or entirely absent, the stigma 

 has the appearance of a superficiai glandular structure upon or beneath the apex 

 of the style or of its arms. If these arms are long and slender, and covered with 

 long hairs, the stigma has the form of a pencil or tuft of hairs or feathers, as in 

 Grasses; in Solanaceae and Cruciferae the moist surface of the stigma covers a 

 knob-like indented thickening at the end of the style ; in Papaver it forms a many- 

 rayed star on the lobed style. Sometimes the stigmatic portion of the style is 

 greatly swollen, as in the Asclepiadeae, where the two monocarpellary and distinct 

 ovaries cohere by the stigmas ; the true stigmatic surface into which the pollen-tubes 

 penetrate lies in this case concealed on the under side of the stigma \ 



The Nectaries ^. Wherever pollination is effected by insects, glandular organs 

 are found in the flowers which secrete odoriferous and sapid (generally sweet) 

 juices, or contain them within their delicate cellular tissue from which they are 

 easily sucked out. These juices are included under the term Nectar, the organs, 

 which produce them being the Nectaries. The position, form, and morphological 

 significance of the nectaries are very various, and always stand in immediate 

 relation to the special contrivances for the pollination of the flower by means of 

 insects. The nectaries are often nothing but glandular portions of tissue on the 

 foliar or axial parts of the flower ; very often they project in the form of cushions 

 of more delicate tissue, or take the form of stalked or sessile protuberances ; or 

 whole foliar structures of the perianth, of the androecium, or even of the gynaeceum, 

 are transformed into peculiar structures for the secretion and accumulation of 

 the nectar. Since it is quite impossible to treat these organs morphologically in 

 general terms, a few examples may serve to show the student where he will 

 have to look for the nectaries in difl'erent flowers. In Fritillaria imperialis the 

 nectaries are shallow excavations on the inner side of the perianth-leaves near their 

 base, large clear drops of nectar exuding from them ; in Elceagnus fusca a glan- 

 dular annular cushion on the gamophyllous perianth (Fig. 384 ^) ; in Rheum slight 

 glandular protuberances at the base of the stamens (Fig. 391 dr)\ in Nicotiana 

 an annular callosity at the base of the superior ovary ; in the Umbelliferae a fleshy 

 cushion surrounding the bases of the styles united above the i-nferior ovary (Fig. 

 383 hh, p. 559); in Compositse they are also at the base of the style (Fig. 393). 

 In Citrus, Cobcea scaiidens, Labiatae, and Ericaceae, the nectary appears as a develop- 

 ment of the floral axis or receptacle in the form of an annular zone beneath th^ 

 ovary (Figs. 387 d, 390^, /), &c.; in . Cruciferae and Fagopyriim in the form of 

 four or six roundish or club-shaped outgrowths or warts between the filaments, &c. 

 An abortive stamen is converted into a nectary in the Gesneraceae; in Cucumis Melo 

 (the Melon) the whole androecium is replaced in the female and the gynaeceum in 

 the male flowers by a similar organ. As a rule the nectaries occur deep down 

 among the other parts of the flower ; and when they secrete nectar, it collects at the 



^ On the position of the lobes of the stigma in relation to the placentae in different plants, see 

 Robert Brown, Misc. Bot. Works, Ray Soc. 1867, vol. I. pp. 553-563. 



■•^ [Behrens, Die Nectarien der BlUthen, Flora, 1879. — Bonnier, Les nectaires, Ann. d. sci. nat, 

 ser. 6. t. VII.l 



