Morphological Studies toward an Improved Classification of Campanulaceae s. str.

Abstract

Growth and seedling morphology of 144 species representing 30 genera of Campanulaceae s. str. were studied. Two types of seedlings were found: Group A, with an elongated epicotyl and elongated internodes, and Group B, with a shortened (not visible) epicotyl and usually shortened internodes. These two types appear to be correlated with other vegetative characters. Thus, plants from Group A have an opposite leaf arrangement (at least early in ontogenesis), rhythmic seasonal growth with a long dormant period, and sympodial branching. Plants from Group B have a spiral leaf arrangement, continuous growth (at least in the non-flowering period), and sympodial and monopodial branching. Taxa in Group A are distributed mostly in Asia, whereas representatives in Group B occur almost worldwide. The two groups do not coincide with current taxonomic classifications but correspond remarkably well with the distribution of other characters such as pollen-grain morphology and correlate with groups based on molecular analysis; therefore, these two groups may reflect two lineages. Growth and seedling morphology are of taxonomic significance in Campanulaceae and can be used for treatments in conjunction with other characters. Taxonomic changes, which are supported by molecular data, are proposed.