Actual state of carpological studies in the family Campanulaceae Juss. with regard to its systematics

Abstract

The systems of the Campanulaceae Juss. introduced by the end of the 20th century used external morphological characteristics of the fruit. However, they significantly differed one from another by the number of subfamilies and tribes. In the system of Campanulaceae s. str. A. Kolakovsky (1995) distinguished four subfamilies, 22 tribes, and 49 genera on the basis of carpological features. Due to this fact, his system is “artificial” and does not correlate with other treatments of this family. The carpological system of Campanulaceae s. str. resulted from the detailed classification of fruits proposed by A. Kolakovsky that reflected the tiniest differences in the mode of formation of openings in the capsule, the location of lignified tissues (axicorns) and the shape of the axicorns. A. Kolakovsky distinguished 43 types of fruits, combined into two groups: non-axicorn-type and axicorn-type. Unfortunately, this classification proposed essential fragmentation of genera and establishment of many new taxa that are not acceptable at present. Molecular and complex studies have led to the integration of Campanulaceae s. str. with related families and the recognition of Campanulaceae s. l. consisting of five subfamilies: Campanuloideae Burnett, Cyphioideae (A. DC.) Walp., Cyphocarpoideae Miers, Lobelioideae Burnett and Nemacladoideae Lammers. The most primitive and diverse in carpological aspect is Campanuloideae that is characterized by superior and inferior, isomerous and oligomerous, dry and fleshy, dehiscent and indehiscent fruits. The fruits in the other four subfamilies are mostly dimerous, superior or semi-inferior, low-seeded, loculicidal capsules with apical valves. Researchers of the Campanulaceae use inconsistent fruit classifications, therefore, only several examples of applying the carpological data to taxonomy are known at generic and infrageneric level. Some features of the Campanulaceae have not been properly studied, in particular: vertical zonation of the gynoecium, placentation, the ovary position and anatomy of the fruit wall. Therefore, the state of knowledge on the evolutionary carpology of Campanulaceae is unsatisfactory. For possible usage of the carpological information in systematics of the Campanulaceae family, it is important to conduct complex studies of fruits as the terminal stage of the flower morphogenesis. Keywords: bellflower family, subfamily, tribe, axicorn, capsule, fruit dehiscence