Anatomical fruit structure and dehiscence in Campanula patula L.
Andreychuk R.
e-mail: roksolana_roksa@i.ua
Ivan Franko National University of Lviv, Ukraine

Is was revealed that dehiscence of the capsule in Campanula patula is proceeded through crescent slits on the lower margins of the oval depressions located on the septa radii in the upper part of the ovary. Slits are formed by the axicorns which are attached to the ovary roof and partly to the central column. The lignified axicorns and vascular bundles are the only lignified tissues of the fruit.

Campanula patula belongs to the section Rapunculus (Fourr.) Воіss. of the genus Сampanula L. This section is characterized by obovoid upright fruits, which are opened with pits located near the top or at the middle height of the ovary. In our material, capsules of C. patula have three, sometimes four, locules. Seeds are numerous in each locule. After anthesis three oval depressions (four when locules are four) are formed near the top of the capsule, in the interfascicular areas of the fruit, on the radii of the ovary septa. Crescent slit is formed on the lower margin of each depression. Later, the lower margin of slit bent outward, allowing seeds of two neighboring locules to fall out by shaking. 
Fruit openings appear through the specific inner ovary structures, named axicornes by A.Kolakovskiy (1995). It was revealed that axicorns are attached to the ovary roof and the central column. We have showed that axicorns are composed by the band of the lignified parenchyma of the inner layer of the fruit wall and septa. During the fruit ripening axicorns are lignified and shorten forming the openings in the ovary wall and allowing seeds to fall out. Other parenchyme tissues of the fruit wall are not lignified, like all tissues of the septa above and below axicorns. In the parenchymatous fruit wall there are 3-4 vascular bundles opposite each locule. Three vascular bundles are also located in the central column on the septa radii. These bundles supply placentae with growing seeds.
Thus, it has been established that axicorns in C. patula are locally lignified parts of the ovary septa. The histological structure of the capsule is characterized by the absence of lignified elements, except axicorns and vascular bundles. The same histological structure of the fruit was found in C. persicifolia. However, in C. persicifolia openings are located in the middle height of the capsule and axicorns are attached to the central column only.