Euphorbia obesa is a peculiar, almost ball shaped dwarf
succulent plant that resembles a stone. It can grow to 20 cm in
height with a diameter of 9 cm. It is a single-stemmed, unbranched,
firm-bodied plant. The stem is usually 8-angled and grooved, subglobose
(almost spherical) in shape, elongating and becoming cylindric as
it gets older. Younger plants have a rounded sea urchin-like shape.
The rotund stem is mottled grey-green in colour with dull purple
transverse bands. It has a tapering tap root. The leaves are very
rudimentary and soon drop off. Euphorbia obesa is dioecious,
i.e. male and female flowers occur on different plants. All euphorbias
have a complex floral arrangement that is termed a cyathium (a cup)
and this is the unit of the inflorescence. A cyathium contains many
highly reduced male flowers or a single female flower. In Euphorbia
obesa, the cyathia appear in summer, from "circular flowering
eyes", situated along the tops of the angles, near the growing
tip, on the stem. They are produced on fork-branched peduncles (flower
stalks), have minute bracts and are finely hairy. The cyathia are
cup-shaped to 3 mm in diameter, expanding in the female. The fruit
is a slightly 3-angled capsule , up to 7 mm in diameter that explosively
releases small rounded 2mm diameter mottled grey seeds when mature.
The peduncles do not persist, and fall off after the seed has been
Euphorbia obesa is a rare endemic of the Great Karoo, south
of Graaff-Reinet in the Eastern Cape. Over-collecting by collectors
and plant exporters almost resulted in the plant becoming extinct
in the wild. Today it is protected by national (Nature Conservation)
and international (CITES) legislation. The plants occur in karoo
vegetation among Beaufort shale fragments, where they grow in full
sun or in the partial shade provided by dwarf karoo shrubs. They
are very well camouflaged and difficult to see. The habitat is very
stony and hilly with summer rainfall ranging from 200-300 mm per
annum, falling mainly in thunder showers. Summers are very hot:
the average daily maximum about 26 degrees centigrade and the minimum
about 11 degrees centigrade. Light frost occurs during the winter
Professor Peter Macowan (1830-1909), a botanist from Gill College
in Somerset East, discovered Euphorbia obesa near Graaff-Reinet
in 1897. He collected this peculiar ball shaped succulent plant
and sent it to the Royal Botanical Gardens, Kew. It flowered in
their succulent house in 1899 when a description was drawn up and
the plant named by Joseph Dalton Hooker (1817-1911). Today it is
one of the most sought after succulent plants of South Africa.
The genus Euphorbia was established by Linnaeus in 1753
and commemorates Euphorbus, the 1st century physician to King Juba
II of Mauritania, who is thought to have used plants, such as euphorbias,
as medicine. It is a large genus and consists of about 2000 species.
Not all are succulent. Of the ± 270 species that occur in
South Africa almost 200 (74%) are succulent. Euphorbias are widespread
in southern Africa, ranging from the north to the south, east to
west, from the coast to the high Drakensberg escarpment and Lesotho.
They vary from dwarf plants a few centimetres high to large trees
such as the naboom, Euphorbia ingens that can grow up to
15 m tall. Most succulent euphorbias are common in the semi-arid
parts of South Africa. The Eastern Cape is especially rich in Euphorbia
species. Most of these make splendid garden subjects and are excellent
for the hot, dry garden. Euphorbias have a milky latex which is
poisonous and is especially irritant to tender or cut skin and the
eyes and all plants should be handled with care.
Growing Euphorbia obesa
Although Euphorbia obesa is still rare in its habitat it
is well established in cultivation. Hundreds of thousands of plants
are produced annually by the horticultural trade in America and
Europe. This is an example of ex situ conservation and one
can safely assume that more plants exist in cultivation than in
the plant's native habitat.
Euphorbia obesa is best grown as a pot plant in a sunny
position such as a window sill or stoep (verandah) but can also
be grown out of doors in the Karoo and other desert gardens where
frost is not too severe. It does best in a gravely shale based soil,
but is tolerant of a wide range of soil types. Good drainage is
essential. Water sparingly during the summer months and keep dry
in winter. It is a slow growing long lived plant and once established,
it will be content in its position and with its soil for years.
It can tolerate moderate shade, and a plant that has been growing
in shade should be slowly hardened off before placing it in full
sun as the plant will be severely scorched if moved too suddenly
from shade into sun.
Euphorbia obesa is easily propagated from seed sown during
spring or summer. Sow in a sandy to gravel-rich, well drained potting
soil in a sunny warm position and in a standard seed tray. Cover
seed with a thin layer of sand (1-2 mm) and keep moist. Germination
occurs within 3 weeks. The seedlings have a slow to medium growth
rate and can be planted out into individual bags as soon as they
are large enough to handle. Flowering can be achieved within 5-8
years. Plants can be hand pollinated with a small paint brush. Rub
pollen onto the brush and transfer to stigmas of female plants.
Remember to cover the female plants with a stocking or a net to
catch the seeds, otherwise the capsules will shoot them far and
Legislation affecting Euphorbia obesa
Please be aware that Euphorbia obesa is protected by both
national and international legislation:
On a NATIONAL level, this legislation differs from province to province
and is policed by the Nature Conservation authority. In the Western
Cape (and probably the Eastern and Northern Cape who were all part
of the same province in 1974 when the ordinance was passed) Euphorbia
obesa and 8 other species, are listed on Schedule 3 (Protected
Flora) and one requires a permit from Nature Conservation to collect,
cultivate and sell Protected Flora. When buying protected flora,
make sure that the seller is registered with Nature Conservation
and that they issue an Invoice. For more information, please contact
the Western Cape Nature Conservation Board, Private Bag X9086, CAPE
TOWN, 8000, telephone (021) 483 3539 / 483 3170, fax (021) 483 4158,
or your provincial authority.
On an INTERNATIONAL level there are ten species of Euphorbia on
Appendix I, but Euphorbia obesa, and all other succulent
species of Euphorbia are listed on Appendix II of CITES, i.e. the
Convention on International Trade in Endangered Species of Wild
Fauna and Flora. This means that each and every Euphorbia obesa plant or piece of a plant being carried over an international border
requires a CITES Export Permit issued by the authority of the exporting
country, and a CITES Import Permit issued by the authority of the
importing country. Seed, flasked seedling cultures and pollen from
artificially propagated plants are exempt and may be traded without
a permit. Buyers are advised to make sure that the seller is a reputable,
registered dealer and that an invoice is issued with the sale. For
more info on CITES, please visit their website:
www.cites.org. They give a great deal of info. including a list
of national authorities of all member countries.
Finally, please note that the above legislation has nothing whatsoever
to do with plant health and cleanliness legislation that is applicable
to the import/export of all plant material and which is usually
under the jurisdiction of the Dept./Ministry of Agriculture.
- White, A, Dyer, A. & Sloane B. 1941. The succulent Euphorbieae.
Abbey Garden Press, Pasadena, California.
- Mitich, L. 1983. The subglobose Euphorbias. The Euphorbia Journal
vol. 1 32-38. Strawberry Press
- Jackson, W.P.U., 1990, Origins and Meanings of Names of South
African Plant Genera, U.C.T. Printing Dept., Cape Town.
Author: Ernst van Jaarsveld, with legislation
info by Alice Notten
Kirstenbosch National Botanical Garden