Genetical and Cytological Investigations on Viola Tricolor L. And V. Arvensis Murr

HE European species of the genus Viola are divided into three sec-T tions, mainly according to the form of the stigma: Nominium with the stigma developed into a papilla at the top of the style, Dischidium with the stigma expanded disc-like, and Melanium with a large, concave, capitate stigma (GINGINS 1823).Some of the best-known representatives of the Nominiurn section are Viola silvestris RCHB., V .canina RCHB., V .odorata L., V .palustris L., and, in North America, V. cucullata Am.The sole representative of the Dischidium section is V .biflora L. The most widely distributed species of the Melanium section are Viola tricolor L. and V .arvensis MURR., their geographical distribution coinciding with that of the section itself.The other species belonging to this section are for the most part alpine, in contrast to tricolor and arvensis, which belong to the lowlands.The best-known of the remaining species are V. Zutea HUDS., V .calcnrata L., and V .cornuta L. In North America, there is V .Rafinesquii GREENE, which is closely related to arvensis.Numerous species hybrids have for a long time past been known in the Nominiurn section; it is only during recent years however, that such have been recognised to any great extent in the Melanium section.CREPIN (1863, Fasc.3, p. 17) mentions a hybrid between V .lutea and V .tricolor, and FOCRE (1881, p. 48) mentions among hybrids belonging to this group only V .calcarafa L. X tricolor L. WITTROCK (1897, p. 107-115) seems to have been the first to recognise the hybrids between V. arvensis and V .tricolor, though they are by no means altogether rare.He also describes: quite correctly, the hybrid between V. elegantula SCHOTT (= latisepala WETTST.) and 1' .cornuta L. Finally, he has given a historical survey of the pansies Hereditas 1'111.cult it is to distinguish the heterozygotes even from the yellowish white ())light yellow,).