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Uncarina roeoesliana

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Photo by Jerry Wright,
GP Desert.

Author:  Werner Rauh, 1995
Origin:  Madagascar
Soil:  Mix
Water:  Maximum
Sun:  Medium
Thickness:  14 Centimetres
Height:  2 Meters
Flower:  Pale - Dark Yellow
Propagate:  Seeds/Cuttings
Names:  -
Synonyms:  -

This member of the Pedaliaceae family was described by Werner Rauh in 1996. It's from Madagascar, growing in well-drained soil with lots of water and sun. The stems reaches for two meters with a base of 14 centimetres. The flowers are pale to dark yellow, and it can be reproduced by cuttings as well. 

The genera is named for the Uncarina tribe of Madagascar. The species is named after Walter Röösli, a Swiss optician and lover of botany, travelling Madagascar.

There are two very distinct leaf forms on Uncarina roeoesliana, and in the last couple of years, they have been mixed. Doesn't exactly make it easy to ID your plant!

I found this informative piece from: Chuck Hanson - Arid Lands Nursery. An interesting feature of this genus is its pollination strategy. Although the sexual parts of the flowers are apparently normal, the anthers never shed pollen. If one tries to pollinate the flowers of an Uncarina, the usual method of using a small brush to transfer pollen doesn't work. There are several families of pollen eating beetles. Beetles are not as skilful fliers as are bees, moths, etc., therefore they need a good landing platform so they can feed without flying. The corolla limb of Uncarina is a perfect landing platform. Some even have nice "runway" markings such as stripes and dark floral tube markings. Remember that these flowers are oriented horizontally. The stigma has two lobes, one upright and one hanging down into the tube, partially blocking ingress. The beetle pushes past this stigma lobe to get to the anthers. Each anther has a lobe that hangs down into the floral tube. The beetle begins feeding on this lobe. As it bites into the lobe a slit pore above the lobe opens and pollen the consistency of toothpaste is deposited on the head and thorax of the beetle. When the beetle exits the flower the stigma lobe offers no resistance. As the beetle enters another flower and pushes past the lower stigma lobe the upper stigma lobe is moved down on top of the beetle and scrapes the pollen off. Pollination!