Flower visitors of Streptocarpus teitensis: implications for conservation of a critically endangered African violet species in Kenya

Background The African violets are endangered plant species restricted mainly to the Eastern Arc Mountains biodiversity hotspots in Kenya and Tanzania. These plants grow well in shaded environments with high humidity. Given their restricted geographical range and published evidence of dependance on insect vectors to facilitate sexual reproduction, understanding their pollination biology is vital for their survival. Methods We conducted an empirical study using flower visitor observations, pan trapping and bagging experiments to establish the role of flower visitors in the fruit set of a locally endemic and critically endangered species of African violet in Taita Hills, Kenya, Streptocarpus teitensis. Results The study found that fruit set is increased by 47.8% in S. teitensis when flowers are visited by insects. However, it is important to note the presence of putative autogamy suggesting S. teitensis could have a mixed breeding system involving self-pollination and cross-pollination since bagged flowers produced 26.9% fruit set. Conclusions Insects appear to be essential flower visitors necessary for increased fruit set in S. teitensis. However, there is evidence of a mixed breeding system involving putative self-pollination and cross-pollination suggesting that S. teitensis is somewhat shielded from the negative effects of pollinator losses. Consequently, S. teitensis appears to be protected to a degree from the risks such as reproduction failure associated with pollinator losses by the presence of a safety net in putative self-pollination.

Morphometrical and biological indicators in definition decorative representatives to the Saintpaulia H. Wendl.

Long-term researches showed that representatives of cultivars of Saintpaulia H. Wendl. are most long flowering plants of family of Gesneriaceae Dumort. in the protected soil of Oles Gonchar Dnepr National University Botanic Garden. The decorativeness of cultivars was determined on morphometric and biological descriptions: to correlation to the diameter of flower with a width and long sheet plate, to the form of flower, double, fringed of edge of petal, and also general proportion of corolla, the phenology of flowering and other. Descriptions of the most perspective cultivars of Saintpaulia getting top marks on the scale of estimation are considered. A brightness, chromaticity, maintenance of these qualities during all life of flower (more than 2 months at some cultivars), beauty and harmoniousness of picture at multicoloured Saintpaulia, was taken into account. Studies and observations were conducted in the stock conservatory of the laboratory of tropical and subtropical plants from 1997 to 2018.We used garden classification of The Special Comity of The African Violet Society of America – AVSA, scale of assessment of economic-biological and decorative features. A complex evaluation of 60 cultivars from the genus Saintpaulia from the laboratory of tropical and subtropical plants of the botanical garden of the DNU was carried out. It is educed, that most showily plants look with flowers, having a size of corolla, equal to the width of sheet plate, or less than her no more, than on one centimeter. Most objects driven to this article respond to this request and have the highest productivity of flowering. The evaluation of ornamental properties and prognosis of the succesful introduction of 20 taxsons (the sorts: EK-Boy Bykov, ЕК-Belaya Koroleva, EK-Zhemchujniy Zephyr, Arctic Frost, Blue Dragon, Kilauea et al) have been given. Perspective for cultivation in closed soil species have been selected. Modern varieties for indoors greenbelt setting have been listed. The got results served in future for creation of scale of cultivars of Saintpaulia and complex estimation of their decorativeness. All studied cultivars are used in an educational process.