ANGIOSPERMS. 
5^9 
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 superficial 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 Solanacese and Cruciferse 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 
gready swollen, as in the Asclepiadese, where the two monocarpellary and distinct 
ovaries cohere by the stigmas ; the true sdgmatic 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, forrh, 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 gynseceum, 
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 different flowers. In Fritillaria iniperialis 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 Elceagrius fusca a glan- 
dular annular cushion on the gamophyllous perianth (Fig. 384 d) ; 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 inferior ovary (Fig. 
383 hh, p. 559); in Compositae they are also at the base of the style (Fig. 393). 
In Citrus, Cobcea scandens, Labiatae, and Ericaceae, the nectary appears as a develop- 
ment of the floral axis or receptacle in the form of an annular zone beneath the 
ovary (Figs. 387 d, 390^, /), &c. ; in Cruciferce and Fagopyrum 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 Gesneracese ; in Cucumis Meto 
(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 EUithen, Flora, 1879. — Bonnier, Les nectaires, Ann. d. sei. nat. 
ser. 6. t. VIL] 
