A species well worth growing for its long flowering period. It is a tuberous-rooted sort that comes from Madagascar. The tubers appear the first year from seed and the growth above the tuber will die off that year leaving the tuber to overwinter. It produces new growth the following year. The tuber normally grows above the ground in the wild, so do not be tempted to plant it under the soil or it will rot off. These plants can easily be propated from cuttings, but then the tuber does not come back and the vegetative part will only last a year, unlike cuttings taken from Impatiens flanaganae which do produce a tuber. Therefore, the flowers of tuberosa need to be pollinated to get seed in order to produce a plant with a tuber.
The flowers are produced in abundance, close to the top of the stem in full view. They are normally pollinated by bees, but can easily be pollinated by hand. The colour of the flower is dark pink with very little variation, unlike Impatiens bicordata which has a large range of colours.
The minimum temperate in the winter should be about 10°C and you must keep the tubers dry to avoid rot. In summer it can be kept outside, but preferably in the shade. It can take high temperatures, but keep it well-watered then. Normal potting soil is fine; it does not require special mixtures, but avoid soil with a high clay content. The only problem with pests is likely to be red-spider mite and keeping the air moist will help to combat that. I hope to offer this sort next year on my list.

 

Impatiens tuberosa

Impatiens tuberosa

Impatiens tuberosa

Impatiens tuberosa

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All Uncarinas originate from Madagascar. There are about 15 species and all species are in cultivation. There are three flower colours to be found: red, white and yellow. The latter is the most common. Only one species has a true caudex, Uncarina roeoesliana. It is also the easiest one to flower; it can already flowers when still small. The rarest is Uncarina leptocarpa, the only white-flowering species.
One reason that Uncarinas are not common in cultivation is that the seed does not germinate easily. Why this is, we do not know. Propagation by cuttings is not a substitute because they do not root easily either. In short: a difficult sort to propagate.
But, once you have managed to get yourself one, it is relatively easy to grow. It needs plenty of warmth and plenty of water in the growing season, but keep it dry in the winter. In the wild they can grow up to four metres, but do not expect that in your greenhouse or window sill.

Uncarina species

This is one of a number of new species from Madagascar that has been brought into cultivation over the last few years. It has a creeping stem which will elongate and climb into shrubs when ready to flower. There are two colour forms, the white one seen here and a green one which is more common. It requires a winter temperature of 15°C to do well. It is not difficult to cultivate provided it is kept shaded in the summer.
It can be propagated from cuttings or, although rarely available, from seed. Seed can germinate within 24 hours which tends to be common in Asclepidaceae anyway. The stems of petignatii are similar to those of C. armandii and C. simoneae; some people would call it “like dead braches”, but don’t be fooled; they are obviously not dead. The vegatative stems are normally thick, but when they start to flower, they elongate and become very thin.
Please note that the leaves you see in the picture below are from a different species; the petignatii was growing in amongst it.

A photo of the green variety can be seen in Art Vogel’s album.

Ceropegia petignatii

Ceropegia petignatii


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Just added to the website: photos of Impatiens mandrakae and sp. China yellow.

The mandrakae is a small creeping species from Madagascar, quite easy to grow, with tiny translucent green flowers. Definitely not hardy.

I do not know the botanical name for sp. China. If anyone can help ….? It looks a bit like I. stenantha, but it is less speckled than stenantha. I do not know if it is hardy; I keep it at 10 degrees C.

Impatiens sp. China

Impatiens mandrakae