Cytotaxonomical studies on the genus Galium. A preliminary report

Cytological studies on the Rubiaceae with special references to the genus Galium have been done by HOMEYER (1936) and FAGERLIND (1937). EHRENDORFER (1949, 1954, 1955, 1956) described the phylogeny of the section Leptogalium. More detailed cytological and cytotaxonomical investigations appeared by HANCOCK (1942) (Galium palustre L., Galium debile Desv. and Galium uliginosum L.), CLAPHAM (1949) ( Galium palustre L.), EHRENDORFER (1949, 1953) (Galium pumilum Murr.) 1955 (Galium rubrum L. and Galium pusillum L.) and of Galium boreale L. by Löve and Löve (1954) and more recently by RAHN (1961). FAGERLIND (1937) and, previous to him, HOMEYER (1936) determined the chromosome numbers of many Galium species. Later investigations by EHRENDORFER (1949, 1955, 1956, 1961), LÖVE and LÖVE (1954, 1956), PIOTROWICZ (1958), POUQUES (1949), RAHN (1960, 1961) and REESE (1957) confirmed and supplemented this list of chromosome numbers. Many investigators have paid attention to the genus Galium. However, their studies have concerned only with some critical species or groups. Many taxonomical problems remain concerning the genus. SCHUMANN (1891) in ENGLER and PRANTL „Die Natürlichen Pflanzenfamilien” divided the genus in 14 sections which are very distinct morphologically. However, within these sections it is often very difficult to define exactly the morphological differences between the species.