Conophytum rugosum 海参

My other three problem conos are all in the section Cylindrata. Conophytum rugosum is wide-spread through Namaqualand and is much easier to see, such that I have found and photographed a number of colonies as have my various cono-ecotourist friends. It can be found growing on the 500 million year old eroded gneiss domes that are so characteristic of the area along with C. pellucidum and pageae; C. obcordellum subsp. stenandrum and C. minutum can also occur on the same domes in the southern part of its range. The colonies of C. rugosum that I have observed have tended to grow in grit pans near the base of the domes, whereas C. pellucidum and pageae have been higher up. When the winter rains fall, the run-off from the domes can be expected to create a moister environment on the low parts of the domes where they start to flatten out, so I wonder if problems in growing the species are associated with us giving it too little water? There is some variation in the colonies that I have seen, particularly in the colour of the bodies that can vary from green to brown. Flowers are small suggesting that it has given up the idea of attracting pollinators and that it is happy with self-fertilisation.

The first problem with C. rugosum is germinating the seed. I have always had a low success rate, maybe 5 – 20%, and germination is very slow, usually taking at least a month. I sow in January with bottom heat that raises the temperature about 5^oC above ambient. I do not keep good records, but get the impression that germination is best when January is cold and bright. This results in my seed unit having a wide diurnal variation from about 8^oC at night to over 20^oC in the day and I suspect that this wide fluctuation is beneficial. Seedlings usually grow on quite well for the first couple of years but then seem to run into problems and start dying or at least some heads in a clump die or fail to expand when watered in the autumn. This is a problem that also occurs with various forms of C. roodiae and C. buysianum which are also in the section Cylindrata. The best solution to perpetuating these taxa seems to be to regularly pull the heads apart and replant in new compost. This is easier than it sounds because C. rugosum, C. buysianum and most forms of C. roodiae are mat-formers and each head independently forms roots as the mat grows. So they can be easily pulled apart into separate heads that already have roots. C. reconditum grows in the same way but does not seem to suffer from the same die-back problem, it simply succumbs to sunburn if not given some shade in the summer. I have maintained some stocks of C. rugosum for quite a long time but they eventually seem to disappear unless repropagated from seed.