Morpho-Anatomy of the Gynoecium and Fruit in Three Ornamental Members of Campanuloideae (Campanulaceae)

Abstract

Gynoecium and fruit micromorphology and anatomy were studied using light microscopy in three species of Campanuloideae belonging to the tribes Cyanantheae (Platycodon grandiflorus), Wahlenbergieae (Jasione montana), and Campanuleae (Adenophora liliifolia) of the native and cultivated flora of Ukraine, to elucidate structural adaptations for fruit dehiscence. The studied species differed in flower/fruit orientation, carpel number, ovary insertion, and capsule-opening position, and the information provided a background for the discovery of common anatomical features influencing fruit dehiscence. In the studied species, the synascidiate and symplicate zones in the ovary and prominent placentae were found to be located near the mid-region of the ovary. The distinct innervation of the ovary wall and ovules was described. In P. grandiflorus, the septa and fruit wall contained a lignified parenchyma in a subepidermal position, while in J. montana and A. liliifolia, lignification was observed only in proximal portions of the septa, above the placenta (J. montana), or was noted as a narrow strand from the ovary base to the mid-region, called “axicorn” (A. liliifolia). In all the studied species, unlignified endocarpium was detected. The semi-inferior capsule of P. grandiflorus has been defined as a capsule of the Forsythia-type, with a sclerenchymatous layer in the inner zone of the mesocarpium. In J. montana and A. liliifolia, a new histogenetic type of capsule is described as Campanula-type, without lignified layers in the fruit wall and with lignified tissue in the septa, which enabled dehiscence. Our study proposed for the first time the classification of the capsules found in the studied species based on the development of openings in the superior or inferior regions of the fruits. The upright fruits of P. grandiflorus and J. montana reveal incomplete dorsiventral dehiscence in the superior region of the fruit, while dehiscence of pendent fruits of A. liliifolia is hippocrepiform-septifragal interlocular and occurs in the inferior region of the fruit at its base, as revealed previously in Campanula latifolia fruit.

Keywords

• adenophora
• jasione
• platycodon
• axicorn
• fruit dehiscence
• gynoecium
• inferior capsule