Date of this Version
These investigations are the outgrowth of a study, begun in 1914 at the instance of the late Professor C. E. BESSEY, of parthenogenesis in Taraxacum vulgare (Lam.) Schrk. and T. laevigatum ( Willd.) DC. These two species are the common ones in central United States, being respectively designated as Leontodon Taraxacum L. and L. erythrospermum (Andrz.) by BRITTON and BROTVN (3). In 1917 the existence of ameiotic parthenogenesis in both species was confirmed (23) and certain pollen abnormalities briefly described. These abnormalities have invited more critical analysis as a means of throwing light upon certain phases of variation and degeneracy, and likewise upon the problem of synapsis. The study of non-cytological variations has been directed largely to leaf characters. This is due to frequent references in the literature of Taraxacttm to "polymorphy" and to the wholesale erection of species (cf. Index Kewensis 10).