Fruchtbiologische Untersuchungen an Heliotropioideae (Boraginaceae).: I. Die Ontogenie der monospermen Früchte von Heliotropium supinum L.

Abstract

Ontogeny, morphology, and anatomy of the one-seeded fruit of Heliotropium supinum have been investigated by LM and SEM. Prior to anthesis the bicarpellate gynoecium develops symmetrically. Four basal septa build chambers which completely surround the ovules and separate them from each other. After anthesis usually only one ovule from the abaxial carpel develops into a fertile seed. Around this seed the outer wall of the gynoecium and the adjecent basal septa develop into the typical pericarp of a Heliotropium nutlet. The other nutlets crush. The sclerified endocarp is made up by the inner epidermis and additional cell layers originating from the inner subepidermal layer. The mesocarp is parenchymatous and constitutes an apical solid hump by which the stylar base is overtopped. The exocarp is one-layered.