76 ANGIOSPERMAE—DICOTYLEDONES 



when present. The. latter may be double, simple, or appear merely in the form 

 of transverse ridges. (Bunias, Ochthodium, Myagrum, Isatis, Peltaria, Neslea, 

 Camelina.) 



IV. Brassiceae. 



Both lower and upper nectaries are present, and are never united. The lower 

 arc prismatic, flat at the top, and inserted at the posterior side of the short stamens. 

 The upper are always simple, either angular and columnar, or irregularly three- 

 sided, and never in the form of a transverse ridge. (Succowia, Erucastrum, Eruca, 

 Diplotaxis, Brassica, Melanosinapis, Sinapis, Moricandia, Rapistrum, Raphanus, 

 Crambe.) (Cf. the abstracts given by Polak in the Bot. Centralbl., Cassel, xii, 1882, 

 pp. 264-6, and xix, 1884, pp. 9-1 1.) 



The position of the nectaries relatively to the anthers is such that insects 

 probing for nectar must come into contact with all or at least some of the latter 

 with one side of their body, and touch the sUgma with the other side. The more 

 unfavourable the position of stamens and pistil for this purpose, the more is automatic 

 self-pollination furthered. As regards concealment of nectar, most Cruciferae belong 



Fig. 26. Nectaries of some Cruciferae (after Prantl). Seen rom the side, after removal of sepals, 

 petals, and stamens. A. Hesperis Matronalis L, B. Selenia aurea Nutt. C. Sisymbrium strictis- 

 simum L. Brassica Napus L. 



to the flower class EC, a few with vertical sepals (Sinapis, Erucastrum) to E, and 

 others, especially those with violet, red, or blue flowers (species of Matthiola, Cakile, 

 Cardamine) to C. The last are visited by decidedly more numerous and more 

 highly specialized insects, adapted to effect pollination, than is the case with the white 

 or yellow flowers of Cruciferae belonging to the class EC. While these are visited 

 chiefly by flies (especially Syrphidae), by the less specialized bees (Apidae), and 

 to a lesser extent by other Hymenoptera (Sphegidae), as well as by beetles and 

 Lepidoptera, the violet, red, or blue flowers with concealed nectar receive many 

 visits from long-tongued bees and from Lepidoptera. Individual species (Hesperis 

 tristis Z.) are characteristic Lepidopterid flowers (L). 



49. Matthiola R. Br. 



Conspicuous flowers with deeply concealed nectar, secreted by glands at the 

 bases of the two short stamens. 



168. M. incana R. Br. (Knuth, ' Bloemenbiol. Bijdragen,' Bot. Centralbl., 

 Cassel, Ixx, 1896, pp. 337-8.) — Homogamous bright red flowers, smelling of cloves. 

 The sepals are erect, and cohere above. They closely surround the claws of the 

 petals, so that these form a tube 15 mm. long and 2 mm. wide, expanding above 



