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Euphorbia meloformis Aiton

Rikus van Veldhuisen.

Introduction
Euphorbia meloformis is probably the best represented Euphorbia in our collections. And so there are not many of the about 500 succulent species of Euphorbia's about which was written more than about Euphorbia meloformis. The reason that your writer still picks up his pen is the fact quite some recent knowledge can be added to the already existing information.

Euphorbia meloformis is a very 'ancient' species, because she was already described in 1789, by William Aiton (gardener of king George III) in the second part of the first edition of the Hortus Kewensis. He called her the 'melon-shaped spurge' and stated that she was brought to England in 1774 by Francis Masson. After this many famous botanists quite deservedly took an interest in this species according to numerous publications about E. meloformis that followed.
By the way, in the 'Euphorbia-bible' White, Dyer & Sloane talk about an 'apple-shape' instead of a 'melon-shape', which is much more appropriate in my opinion.

Localities
The typelocality of Euphorbia meloformis is near the Zwartkops River, north-west of Port Elizabeth. The localities around Port Elizabeth, in the vicinity of the ocean, form the most western distribution-area of Euphorbia meloformis.
Over a hundred km to the east there's a second distribution-area in the neighbouthood of Grahamstown. The plants in this area differ from one population to another, but also from one plant to another. This has caused much confusion. And on top of this there is a very closely related 'species' growing nearby, Euphorbia valida, at several locations a bit further away from the ocean, to the north and west of the two mentiond areas.
And again at more than a 100 km to the east of Grahamstown, a bit north of Peddie, plants were found in 1975 which look very similar to Euphorbia meloformis. They deserve though a separate status.

These three geografically clearly separated distribution-areas form the base for this article. Therefore I will introduce them a bit more intensive by describing the characteristic features of the plants and by some accompanying pictures.

Port Elizabeth.
Plants, on which the original description in 1789 is based, originate from the neighbourhood of Port Elizabeth.
Some striking characteristic features of Euphorbia meloformis from around Port Elizabeth are:
- plants stay rahter small, they grow to max. 12 cm in diameter
- they have rounded ribs with red-brown cross-bands
- the flowerstalks of the male plants remain longer on the plant than those of the female plants
- they have practically always 8 ribs and branch only seldom
- the seedlings are already from the start almost sphearical and their little leaves dry quickly.
Having said this, it is however possible to find near Grahamstown an individual plant, which does match the above given features quite well. And also one can find an indivudual plant near Port Elizabeth, whhich looks like the most commen form occurring near Grahamstown. Only the frequency of certain characteristic features differs in the populations from these areas. Because of this the most common appearance of a population at a certain locality is indeed different to th most common appearance of a population at another locality.

It is not a surprise that, after studying the many appearances of E. meloformis and E. valida, Dr. Marloth came to the conclusion that the plants from Port Elizabeth belonged to the variety pomiformis. He also ranked all the other plants, including Euphorbia valida, among the variable species Euphorbia meloformis. Taxonomically seen this can not be right. The type-form can never be degraded to a variety. Though the thougt behind this approach is quite understandable.
Unfortunately all Port Elizabeth-localities are being threatened by town development and her survival in nature is thus most uncertain. Plants from these locations also rarely show up in collections which is quite a shame because they are considered to be the most beautiful form.

Grahamstown

haworthia cooperi var. pilifera
  Haworthia cooperi var. pilifera (J&R176) grows at this locality too.
  corpuscularia lehmannii
  Corpuscularia (former Delosperma) lehmannii grows together with E. meloformis

North and north-west of Grahamstown, just about 100 kilometers east of Port Elizabeth, Euphorbia meloformis is much more common. Most of the plants in our collections are similar with these forms. She also grows nature-reserves, so her survival in this area doesn't seem to be threatened.
These plants also have their own special characteristics which clearly deviate from the type-form.
The differences with other populations that strike the eye the most are:
- the plants show a great tendency to sprout, about 30% of them sprouts in nature
- they have a plain hard-green colour
- they have a thick taproot
- their ribs are sharply angular
- the flowerstalks are relatively long and remain a long time after flowering
- seedlings have usually sharply angular ribs, they are dentated and have relatively large leaves which stay alive much longer.

N.E. Brown noticed these differences too and came to the conclusion that a misunderstanding that has lasted for more than a hundred year, should be corrected. He did this by means of describing a new species: Euphorbia falsa. He did however emphasize the deviating characteristics to much by stating them to be fixed rules. For example, he stated that all plants of Euphorbia falsa were ramified. This couldn't last of course and so E. falsa soon became synonymous with Euphorbia meloformis. So the species Euphorbia falsa didn't last for long. Nevertheless these plants from Grahamtown do differ from the type-form and to deal with these differences taxonomicly Gerhard Max described the plants from Grahamstown as 'forma falsa' in the Euphorbia Study Group Bulletin.


Peddie.
In contradiction with the previous mentioned localities of Euphorbia meloformis this locality north of Peddie was not discovered untill the middle seventies. And again this locality is about 100 kilometers futher to the east.
Quite soon after the discovery of this locality plants from this place were send to Dr. Dyer. Because these plants were so big ( almost 20 cm in height and diameter) he stated that the plants must have been overfed by growing in a very nitrogenous kind of soil. This reaction is not so surprising, but if Dr. Dyer would have visited the locality himself he would have come to another conclusion.
Later he did so anyway, because on the herbariummaterial of Euphorbia meloformis from that locality he wrote"subspecies magna" and changed that a bit later even in "forma magma".
Gerhard Marx shared this view by describing these plants as forma magma in the Euphorbia Study Group Bulletin.
In november 2001 we visited this locality. We were very impressed by the size of the plants. The plants grew in very short and dry grass what made them even more striking. Futhermore the plants had a uncommonly grey/green colour, most of the bigger plants had up to 14 ribs and none of the plants had dryed flowerstalks. These are chararteristics which make them clearly different from
the plants in the other localities. I think the pictures will speak for themselves.
We had had to search a long time for these plants but the plants sure were worth it!

 

Euphorbia valida.

euphorbia meloformis ssp valida
  E. meloformis ssp valida grows quite big, with 8 marked ribs and big thorns

Euphorbia valida can and may not be absent at this discussion of Euphorbia meloformis. Their localities are adjacent and in historie the two species often have been compared and mixed up. This is not very strange because they have more similarities then differences.
Euphorbia valida was described in 1915 by N.E. Brown. He named her 'valida' because he thought the plant was 'valid' (sound). White, Dyer and Sloane spoke of an appropiate name.
This lasted for 80 years, until 1998 when Gordon Rowley degraded Euphorbia valida to be a subspecies of Euphorbia meloformis. Seen the great similarities this sure can be justified, though there are some stable differences. Like the fact that Euphorbia valida becomes much bigger (up to 45 cm), their flowerstalks remain on the plants for a long time and they have a remarkable striped pattern on the body.

 

 

dikkop flats, locality of euphorbia meloformis ssp valida
  Dikkop Flats, locality of E. meloformis ssp valida.

Euphorbia valida has localities as well as at Janssenville as at Somerset East, at the Springbokvlakte near Steyterville and at the Dikkop Flats. The most known locality is the Dikkop Flats, it is a bit more nothren of Grahamstown as the locality of E. meloformis. They are only separeted by the about 10 km long Hells Poort.
Of these four localities the plants of the Dikkop Flats become the biggest and these of the Springbokvlakte stay the smallest.

Present formal status
Like mentioned before Gordon Rowly stated in 1998 in the Euphorbia Study Group Bulletin Euphorbia valida to be a subspecies of Euphorbia meloformis. Immediately after that Gerhard Marx placed in 1999 in the same journal yhe plants from Grahamstown as forma falsa and the plants north of Peddie as forma magna under Euphorbia meloformis subspecies meloformis.
So the picture looks like this:

Euphorbia meloformis Aiton 1789.
                                                       |                                    |
                                  ssp. meloformis              ssp. valida (N. E. Br.)Rowley.
                                          |
                   forma meloformis
                   forma falsa (N. E. Br.) J. G. Marx.
                   forma magna R. A. Dyer ex J. G. Marx

This classification mentioned above justifies the present knowledge of the group of forms around Euphorbia meloformis and the history of this species has been left unimpaired as much as possible.
However it might have been better to give the forma magma the same rank as the subspecies valida.
The forma magma distinguishes itself more from the forma meloformis as does the ssp. valida from de ssp. Meloformis. Above that a forma is always based on a single characteristic feature like the colour of the flowers or on a single deviating indivudual. That’s why a rank of variety fits the plants from the surroundings of Grahamstown better.

koppie with euphorbia meloformis
  Koppie with E. melof. ssp. melof. forma falsa. J&R 102. Grahamstown
  e. meloformis ssp meloformis forma falsa
  E. meloformis ssp. meloformis forma falsa. See its dried flowerstalks bent ober the plant

In 1999 we visited a very small locality of Euphorbia meloformis ssp. meloformis forma falsa, this is its official name now. The 'koppie', at the edge of Grahamstown, was about 200 square meters and some 150 plants grew there. The plants were relatively small, more than half of the plants was sprouting and they had a beautiful striped pattern. Above this they had a very thight bunch of dried flowersstalks. These stalks were bent quite strongly over the plant. This made the plants well hidden between the grass.
The plants from this population keep the mentioned differences in culture too, because little seedlings also show the striking curved flowerstalks.
This all is just an example of how unique and valuable this species with its many appearances is.

Two years later we visited this place again and after searching thoroughly we couldn't find more than 14 plants. The population was decimated. Probably the hope that all the different localities will be preserved will be false, certainly if we look at the situation which South-Africa is in at this moment.
It is of most interest that some Euphorbia-specialists grow these plants further, separated by locality, and make sure that the material will be spread among those who are interested. Only then the unique characteristics of a certain population can be preserved. To my opinion this is more important as the exact name on the label, it could be just 'Euphorbia meloformis', or not? A regular plant?

Literature:
Marx, J. G., (1993) The Sub-globose Euphorbias and Relatives, Aloe 30, No. 3/4.
Marx, J. G., (1988) Euphorbia meloformis Aiton & Euphorbia valida N. E. Brown, Some Observations in Habitat, The Euphorbia Journal, Vol. 5, blz. 95 – 103.
Marx, J. G., (1999) The South African Melon-shaped Euphorbias: The full Picture as known to Date, The Euphorbia Study Group Bulletin, Vol. 12, No.1.
Mitich, Larry W., (1983) The Subglobose Euphorbias, The Euphorbia Journal, Volume 1, blz. 32 – 41.
Rowley, G. D., (1998) Euphorbia Meloformis and E. Obesa, with two newly assigned Subspecies, The Euphorbia Study Group Bulletin, Vol. 11, No. 3.
White, A., Dyer, R. A., & Sloane, B. L., (1941) The Succulent Euphorbiae (Southern Africa), 2 Vols

 


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