Taxonomic significance of the inner structure of the ovary in the genusImpatiens (Balsaminaceae)

Abstract

The inner structure of the ovary inImpatiens was examined from the viewpoint of taxonomy, based on the materials obtained during the 1979 Botanical Expedition to Thailand. The species studied areI. kerriae, I. larsenii, I. hongsonensis, I. psittacina, I. salaengensis, I. charanii, I. kanburiensis andI. macrosepala. It is worthy of special mention that they are all characterized by 4 lateral sepals, large round outer sepals, a nipple-like short spur of the lip and connate wing petals. Contrary to the prevailing information about the ovary ofImpatiens, these Thai species were found to have 4-locular and 4-carpellate ovaries. The arrangement and the number of ovules in a loculus show a tendency of reduction from biseriate to uniseriate and from several to single or none. The species of more advanced type have smaller numbers of ovules and often sterile loculi of the ovary, as represented byI. macrosepala. The types of ovule development were proved to correspond to the degree of specialization of floral characters.