Euphorbia Section Triacanthium Jacobsen. Part 4
Rikus van Veldhuisen
After completion of the series of articles about this very interesting group of euphorbias the number of species has increased by at least three species. The careful reader could have noticed this is in no way a surprise to the writer and several times it was indicated that this was to be expected, and even now it is my opinion that the number of described species does not cover the situation in nature, as there are still many more to be discovered and several species are not fully understood.
Euphorbia patentispina S. Carter.
In the Nordic Journal of Botany Susan Carter described Euphorbia patentispina in 2001. In the Flora of Somalia (S. Carter 1993) she mentioned under the description of the variable species Euphorbia xylacantha, collected material (Lav. & Carter et. al 24849) from a very localized habitat from the Bari Region, northern Somalia, as a possible new species. The more closely spaced spineshields, often slightly curved spines, longer prickles (5 mm.) and yellow cyathia were noticed to be different from the more widely distributed Euphorbia xylacantha. Recognizing this collection as a separate species was not to be made until new material could be collected.
This additional collection was made in 2000 by Thulin, Dahir & Osman at Cal Miskaat, also in the Bari Region in northern Somalia, which also served as the type-collection. It appears that especially the habit of this new plant differs considerably, as Euphorbia patentispina forms round ‘cushion-like’ mounds 25 cm high and 30 cm in diameter. The branches are more slender than those of Euphorbia xylacantha, and arise from a central thick stem, and are very prolific in branching and rebranching. Also Euphorbia myrioclada is mentioned as a close relative, but this species forms a much more loose shrub.
I have no reference of Euphorbia patentispina being in cultivation and so no hints for its cultivation can be given.
Another point of interest is the fact that Susan Carter mentions, while comparing this new species with Euphorbia myrioclada, that the distribution area of the latter extends to Djibouti. This fact was not mentioned in the original description of Euphorbia myrioclada and this original description matches Euphorbia species affinis triaculeata AJB D3 quite well. It makes me wonder whether the plants pictured in Figure 4, 5 and 6, dealt with under the species Euphorbia triaculeata, represent Euphorbia myrioclada.
Euphorbia godana V. Buddensiek, P. Lawant and J. J. Lavranos
One recently described species in this group of related species is Euphorbia godana. It was described by two committeemembers of the International Euphorbia Society and the wellknown fieldresearch expert of succulent plants John Lavranos. He was the one who found it in its natural habitat in the Goda Mountains in Djibouti, together with Leonard Newton in 1976. Living material of one of the two collections has been widely distributed in collections under the name Euphorbia species Lavranos 13176, Djibouti, which should be more correctly Lavranos & Newton 13176. Euphorbia godana makes a densely branched shrublet in nature, up to 30 cm high and 40 cm across. Its habit is of rebranching lateral branches from a central stem and cuttings taken of these branches have never been seen to form the ‘head’ of a main stem. However seedlings grown by the writer do show the thick depressed main stem. Its cyathia attract attention by having a golden yellow to orange colour.
In discussions about this new species some notes were also made about two collections made by the chairman of our society, Alan Butler, in Djibouti. Euphorbia species affinis triaculeata AJB D3 is in my opinion not E. monacantha but is closer to E. triaculeata. Euphorbia species AJB D10 comes so close to Euphorbia godana that it most likely also belongs to this species. It flowers freely in my collection with identical golden yellow flowers. Because it is self-fertile I managed to raise a few seedlings of both Lavranos & Newton 13176 and AJB D10. These seedlings are identical to one another but seedlings of AJB D3 are somewhat different. The only real difference between the two clones of both collectionnumbers I grow is the more densely sprouting habit of the Lavranos & Newton clone. Regarding Euphorbia species affinis triaculeata AJB D3 see also the notes under Euphorbia patentispina for this collection by Alan Butler.
Euphorbia godana AJB D10 is collected near the town Al-Sabieh, south of Djibouti-town, which is south of Tadjoura Bay. The Goda Mountains, the type-locality of Euphorbia godana, are situated north of the Tadjoura Bay.
Euphorbia greuteri N. Kilian, H. Kürschner & P. Hein
For the time being the latest species to be described in this group of species is Euphorbia greuteri, named in honour of Professor Werner Greuter of the University of Berlin-Dahlem. Despite its recent official publication, Deflers (1895) already mentions the foothills of Jabal Urays as a locality where the plant is growing, however it was wrongly identified as Euphorbia triaculeata. A considerable amount of time later in 1964, John Lavranos and Werner Rauh revisited this area during a combined expedition on the Arabian Peninsula. Werner Rauh (1966) even published a picture of this plant in the Cactus & Succulent Journal of America. This plant was again wrongly identified as Euphorbia triaculeata and the publication of this picture was even mentioned in the discussion of Euphorbia triaculeata in this series. In 2002 N. Kilian, H. Kürschner & P. Hein came across this euphorbia population again during their studies of xerotropical Palaeozoic African refuges in the southern coastal mountains of Yemen. They did however recognize it as a new species not identical to Euphorbia triaculeata. Until then Euphorbia triaculeata was the only ‘single-spined’ species occurring in Arabia.
Furthermore it has to be said that Euphorbia greuteri is strikingly different from Euphorbia triaculeata in several aspects. Euphorbia greuteri is a low growing species, only getting as high as 15 cm and has a well developed mainstem. These features are shared with Euphorbia actinoclada and Euphorbia immersa. Also the shape of the spineshields differs in having a much shorter elongation of the spineshield below the main spine than in Euphorbia triaculeata and other species. This feature is also present on plants found by Frans Noltee in Yemen and which is published in Figure 7 in the first part of this series. Unfortunately he forgot the exact locality where he found it, but he could well have used the article of Rauh (1966) to pick places to go to on his trip to Yemen, especially as Rauh pointed out the foothills of the Jabal Urays as a succulent paradise. Not until I can grow seedlings of Noltee’s plants, which then should make the well developed mainstem, can I say for certain that this plant really is Euphorbia greuteri.
Euphorbia species nova, Yabelo, Ethiopia.
Under the species description of Euphorbia actinoclada a tip of a flowering branch is displayed on figure 26 in this series of articles on page 21, number 3 of volume 2 of Euphorbia World. Though it was named here as Euphorbia actinoclada, I now believe it is not this species. I have managed to grow a few seedlings of this rooted cutting which were sown in 2005. One of these seedlings is shown here on the accompanying figure 51. These are noticed for their very slow growth (which might be a result of the growing conditions in my hothouse) and are even after two years still spherical with no side branches at all. This is quite contrary to seedlings of Euphorbia actinoclada, grown under the same conditions, which do form side arms already in their first summer.
A few years ago I received a few small plants from a friend in Germany, which were offspring of plants bought at the nursery of Ernst and Marita Specks labelled as Euphorbia species nova Yabelo, Ethiopia and carried the sales number ES 2732. The small plants flowered this summer and produced also the small, entirely yellow cyathia. Even after five years the main stem of these plants is less than four centimetres in diameter. I assume that the pictured sidearm on figure 26 and the plants labelled as Euphorbia species nova Yabelo, Ethiopia are the same. Also I think it indeed might represent a new species.
As said before this new species is noted for its small, entirely yellow cyathia, but also for its light green and yellowish green patterned body colour. These plants are weakly spined, but the thin and stiff main spine is very sharp, as I noticed unfortunately. Also the main stem is well developed, growing quite broad in contrast to Euphorbia actinoclada and the top is depressed.
In conclusion I can add that this very slow growing species is a very handsome plant and a valuable addition to an euphorbia collection.
For now this completes this series about Euphorbia section Triacanthium. I wish to add a few words of special thanks to Pjotr Lawant, who as all good librarians supplied me with literature that I required, Volker Buddensiek for advice and support and Norbert Kilian for sharing information and pictures.
– Buddensiek, Volker, Lawant, Pjotr, & Lavranos, John J., 2005: Euphorbia godana (Euphorbiaceae) – Eine neue Art aus Djibouti, Kakteen und andere Sukkulenten 56 (2) 2005, p. 43 – 49.
– Carter, S., 1993: Flora of Somalia, Volume 1, p. 330.
– Carter, S., 2001: A new spiny Euphorbia (Euphorbiaceae) species from northeast Somalia, Nordic Journal of Botany 21(6)2001, p. 567 – 569.
– Carter, S., 2006: Flora of Somalia, Appendix, p. 572.
– Deflers, A., 1895: Esquisse de géographie botanique. La végétation de l’Ararbie tropicale au-delà du Yemen, Revue d’Egypte 1:349-370, 400-430.
– Kilian, Norbert, Kuerschner, Harals, & Hein, Peter, 2006: Euphorbia greuteri (Euphorbiaceae) – A new single-spined succulent from the foorhills of Jabal Urays, Abyan, Yemen, Willdenowia 36 – 2006, p. 441 – 446.
– Rauh, W., 1966: Little known succulents of southern Arabia (1-2), Cactus & Succulent Journal (U.S.) 38: 165-176, 207-219.
Euphorbia patentispina in habitat, picture taken 3 km E of Galgallo (photo S. Carter)
A seedling of Euphorbia godana Lavranos & Newton 13176 clearly showing the stout mainstem unlike rooted cuttings do.
A rooted cutting of Euphorbia godana AJB D10 from Al-Sabieh, Djibouti, showing the lesser re-branching habit of this clone.
On close inspection of the flowers of Euphorbia godana AJB D10 one can expect fruits will appear soon.
Habitat of Euphorbia greuteri in the foothills of Jabal Urays facing the Gulf of Aden. (Picture N. Kilian).
Euphorbia greuteri, habit at type locality. (Picture P. Hein).
Euphorbia greuteri, a close-up of the stem showing the details of the spineshields with the short elongation below the mainspine. (Picture M. Meyer).
A still small plant of Euphorbia species nova Yabelo of at least 5 years old.
A two year old seedling, still well under one centimetre in diameter, of the mother plant of figure 26. Not the fourspined spine shields, clearly visible here, when still in the juvenile phase.