Uncarina roeoesliana (2010)

PhotoBy Christine Walker (November 2010)

Uncarina roeoesliana is from the Pedaliaceae, or sesame family. This is a small family of 13 genera and 70 species with strictly Old World distribution in both tropical and dry climates.

My U. roeoesliana comes from Madagascar, as do many of our favorite succulents. The plant can reach 2 meters, so I will sincerely try to bonsai it to keep it a more manageable size. The large leaves are somewhat lobed and very velvety, and the plant develops a nice caudex at the base. The many flowers (which this plant is still producing so far) are yellow and shaped like those of adeniums.

I found an article by Chuck Hanson on the Internet that describes the pollination of this plant, and I include part of the article as follows.

“The sexual parts of the flowers are normal, but the anthers never shed pollen. Instead, pollen-eating beetles push past the 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, completing pollination.”

Chuck Hanson reports that using a small brush to transfer pollen won’t work, so unless I luck out with pollen beetles, I may never see the large, prickly-looking seeds I saw in Internet pictures. This plant can also be reproduced using plant cuttings.

Sun exposure is listed as full to part sun. Bloom time is listed as normally late winter to early spring. the foliage is deciduous. Soil pH requirements are listed as 6.6 to 7.8, which ranges from neutral to mildly alkaline.

As uncarinas are from Madagascar, they are not tolerant of low temperatures. The plants are reported to benefit from lots of water and sunlight during the growing season and then should be kept very dry during the dormant season.