A NGIOSPERMS. 30! 



flower, or they are cushions of more delicate tissue, or sessile or stalked protuberances, 

 or the entire foliar structures of the perianth, the androecium and even the gynaeceum, 

 are transformed into peculiar organs for secreting and storing nectar. As no general 

 morphological account can be given of these organs 1 , a few examples will serve to 

 show where the nectaries are to be sought for in different flowers. In Fritillaria 

 imperialis the nectaries are shallow pits on the inner face of the perianth-leaves above 

 their base, which distil large clear drops of nectar; in Elaeagnus fusca (Fig. 301 rf) 

 they form a glandular projecting ring in the gamophyllous perianth ; in Rheum they 

 are slight glandular protuberances at the base of the stamens (Fig. 308 dr) ; in 

 Nicotiana they are annular weals outside and at the base of the superior ovary; in the 

 Umbelliferae a fleshy cushion forming a disk above the inferior ovary at the base of 

 the styles (Fig. 300 h, ti), and the same in the Compositae also at the base of the style 

 (Fig. 310); in Citrus ; Cobaea scandens, the Labiatae, Ericaceae and other plants, the 

 nectary is a luxuriant growth of the torus forming an annulus beneath the 

 ovary ; in the Cruciferae (Fig. 314 k) and in Fagopyrum (Fig. 315 k) it takes the form 



FIG. 313. Flowers with spur-like formations on the sepals (A) and petals (B, C). A 

 B Epimedium grandiflorwn. C Aquilegia canadensis. 



iscutella hispida. 



of four or six roundish or club-shaped outgrowths or warts between the filaments ; 

 in the Gesneraceae an abortive stamen becomes a nectary; in Cucumis Melo and 

 other species, a nectary takes the place of the androecium in the female flower and of 

 the gynaeceum in the male. Generally the nectaries are found deep down among 

 the other parts of the flower, and if they secrete nectar, it collects at the bottom of 

 the flower, as in Nicotiana and the Labiatae; but sometimes special hollow 

 receptacles are formed for this purpose ; such especially are the sac-like spurs formed 

 by the leaves of tiie perianth (Fig. 313). In Viola only one perianth-leaf forms a 

 hollow spur, which contains two appendages from two of the stamens and receives the 

 nectar which they secrete. The cup-shaped stalked petals of Hellelorus and the 

 slipper-shaped petals of Nigella secrete nectar at the bottom of their cavity and 

 collect it there 1 . 



The ovule. The ovule in Angiosperms usually consists of a distinct and sometimes 

 even very long stalk, ftxtfunick (Opuntia and the Plumbagineae), though this is some- 

 times wanting, as in the Gramineae, and one or two integuments surrounding the 



1 See Behrens, Die Nektarien d. Bliithen (Flora, 1879), for the anatomy of nectaries, and also 

 for the literature of the subject. 



