Rhododendron ur undersläktet Vireya : något om dess karakteristika och användning i nordiska vinterträdgårdar

Abstract: Present essay aims to introduce the reader to central topics regarding Rhododendrons of subgenus Vireya. As a result of a donation, the Swedish University of Agricultural Sciences, received a collection of Vireya from a local amateur grower, Kurt Myllenberg. Since the subgenus Vireya is uncommon in Scandinavian horticulture, the study tries to establish conditions for successful growing. The subgenus Vireya differ from the other Rhododendron species through mainly three characteristics: the presence of two tails, attached to each end of the seed; the ovary-style junction is tapering and the pedicels arises directly from a dome-like base and form an umbel and not a raceme. The subgenus is distributed mostly in the islands of Indonesia and New Guinea, but also from Malaysia to Nepal and in Australia. Since Vireya species mainly grows as epiphytes in the tree canopies, they need high drainage and not too much water. The most used growing medium is compost made by coarse bark and nutriens, sometimes with peat and composted needles from pine trees. As a result of their tropical distribution, all Vireya species need much light to grow well. Species from the highest altitudes needs probably more light than a Scandinavian conservatory can give. For this reason high altitude species may not be well suited for Scandinavian growing, without complement lightning. More suited are the medium or low altitude species which grow shaded in the canopy. Native to tropical habitats, Vireya is tender and need protection from frost but also from over heated green houses. Minimum temperatures should be around 8 °C in winter and not over 28 °C in summer. According to growing habitats at the conservatory of Swedish University of Agricultural Sciences, Alnarp, our species will be planted in raised beds. The recommended growing medium is a compost made mostly of pine bark, and a little of loam and charcoal. Since they have a big range from low subshrubs to high, tree forming individuals, Vireya may be useful in conservatories. While the lowest species constitute the floor, the biggest act as green walls and canopy. The flowers appear in winter as well as in summer and all Vireya seems to be drought tolerant. The present collection contains a broad range of species regarding flower color, leaf form and size. Three more, specified, species may supplement the collection regarding flowers and two more species regarding leaf form.