Streptocarpus - Hybridisation

Hybridisation

Hybridisation of streptocarpus is conceptually very simple. The pollen of one plant (therefore the father) is placed onto the tip of the stigma of another plant (the mother). To prevent unwanted self-pollination of the mother plant, carefully remove its anthers beforehand. To help prevent unwanted cross-pollination, cover the newly fertilised stigma with a small plastic bag. If fertilisation was successful, the seed pod will start to elongate within a few days. As the pod grows, it will start showing its namesake twisted form. Once the pod is mature, it will turn brown, dry off, and split open along the spiralled seams to release the seeds.

Another method that is used to create hybrids is to use radiation or chemicals to alter the genes. For example, irradiation may be used (e.g. xrays, gamma rays) to induce mutations that may give rise to plants with new characteristics. Another example is the use of colchicine to induce polyploidy (multiplying number of chromosomes) in plants, also to introduce new traits.

Over the years, numerous hybrids have been produced. S. rexii was used in many of the early hybrids, and its form is one that we most recognise in modern day hybrids. But more recent hybrids may contain the genes of other species or hybrids. When making a cross, hybridisers keep in mind which traits they wish to bring out or improve in the progeny.

Much hybridising work has been done to produce modern hybrids with an increased range of flower colours and forms, leaf variations, increased flowering periods, and more recently to introduce scent. Thanks to the work of hybridisers, streptocarpus now come in a range of colours. These include reds, pinks, purples, blues, yellows, whites, and near-blacks. The only colour that is so-far not available is a true orange.

Flowers now exist that are multicoloured, striped, spotted, veined, double, larger or smaller, and even fragrant and colour-changing. There are also variegated-leaf varieties, such as S. 'Canterbury Surprise'. Flower stems may be short or tall; leaves may be big or small; flowers may be full or dainty; and there may be one or many flowers per stem.

The following hybrid cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-