CAPRIFOLIACEAE 537 



stigma, which projects beyond the dehisced anthers for about 1-2 mm, so that cross- 

 pollination is favoured. 



Visitors. Kirchner observed Apis and the humble-bee Bombus lapidarius L. 



1229. L. implexa Ait. 



Visitors. Schletterer (Pola) observed the ichneumon fly Gravenhorstia picta 

 Bote (=Anomalon fasciatum Gt'r.). 



1230. L. etrusca Santi. 



Visitors. Schletterer (Pola) observed a humble-bee (Bombus argillaceus Scop.), 

 a Braconid (Bracon (Vipio) castrator F.), and a true wasp (Eumenes mediterranea 

 Krchb.). 



LII. ORDER RUB I ACE AE DC. 



Literature. Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins.,' p. 81, 'Grundriss d. 

 Bliitenbiol.,' p. 63 ; Schumann, ' Rubiaceae/ in Engler and Prantl, ' D. nat. Pflan- 

 zenfam.,' IV, 4, pp. 8-13. 



Our native Rubiaceae are mostly small plants, bearing flowers of white or 

 yellow colour, rarely red or blue, and only made conspicuous by being associated in 

 crowded racemose inflorescences. Nectar is usually sparingly secreted by a fleshy 

 disk on the ovary. Some foreign species, on the other hand (e.g. of Manettia, 

 according to Fritz Miiller), possess deeply concealed nectar accessible only to hawk- 

 moths with a long proboscis or humming-birds with elongated beaks. Among 

 German species only Asperula taurina and A. azurea, perhaps also Sherardia 

 arvensis, belong to flower class L, while the other species of Asperula belong to 

 C, and those of Galium to E. 



Some foreign forms are dimorphous, e. g. species of Hedyotis (according to 

 Treviranus); Borreria, Faramea, and Manettia (Fritz Miiller); Mitchella, Knoxia, 

 and Cinchona (Darwin) ; Chasalia, Nertera, Ophiorrhiza, and Luculia (Kuhn). 

 Darwin (' Diff. Forms of Fls.') enumerates 1 7 genera with dimorphous flowers. 



Fritz. Miiller has described the flower mechanism of Posoqueria (Martha) 

 fragrans, native to Brazil (Bot. Ztg., Leipzig, xxiv, 1866, p. 129; xxv, 1867; p. 80). 



393. Sherardia Dill. 



Flowers bright-violet in colour : perhaps belonging to class L, for the nectar is 

 secreted by a fleshy disk surrounding the base of the style, and concealed in a narrow 

 tube, so that it is most easily accessible to small Lepidoptera. 



1231. S. arvensis L. (Herm. Miiller, ' Weit. Beob.' Ill, pp. 71-2 ; MacLeod, 

 Bot. Jaarb. Dodonaea, Ghent, v, 1893, pp. 385-6; Meehan, Bull. Torrey Bot. CL, 

 New York, xiv, 1887, pp. 238-9 ; Schulz, ' Beitrage,' I, p. 64; Kirchner, 'Beitrage,' 

 p. 61.) Hermann Miiller describes this species as gynodioecious. The hermaphrodite 

 flowers are somewhat larger than the female ones. The former are imperfectly 

 protandrous, for the stamens with dehisced anthers curve out of the flower before the 

 stigmas are fully mature. Not infrequently, however, the stigmas are completely 

 receptive while the pollen-covered anthers are still on the same level, so that 



