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Euphorbia polygona (African Milk Barrel) - A much-branched medium sized succulent plant that is typically seen from 18 to 24 inches tall, but is known to grow 3 to 5 feet tall with great age. It branches from the base with a cluster of 6 inch wide grey-green column like stems of unequal length that radiate up and outwards from the center of the plant bearing tubercles fused vertically into many (between 7 and 20) prominent ridges with inch long spine like peduncles (persistent flower stalks) protruding from each tubercle axil. The cyathia, as the unique flowering inflorescences of a Euphorbia are known as, appear at the stem tips at the axil of the tubercle with individual cyathium emerging at the axil of the tubercle with a cup ringed by five red to dark purple glands - the species is dioecious, and our plants are male and no fruit is produced.
Plant in full to part sun in a well-drained soil. Cold hardy down to at least short duration temperatures to 25 °F. A great plant in the ground or as a large container specimen that because of its spine-like peduncles resembles, but is unrelated to cactus.
This plant is native to the Eastern Cape of Southern Africa from Uitenhage to Albany and while dominant in rocky quartzite fields, it is not restricted to them. There has long been confusion between whether this plant should be called Euphorbia polygona or Euphorbia horrida and plants in this group are often referred to as being in the "polygona complex". Though now considered conspecific (the same species) with the valid name Euphorbia polygona, there are differences between the plant cultivated under one name or the other with the typical Euphorbia polygona having more uniform gray stems covered along the ridges with the woody spine-like peduncles but few actual spines and having dark reddish purple flower-like glands in the cyathia, while the plant known as Euphorbia horrida has more irregular stems held in more open clumps and often white striped with greenish-yellow glands in the cyathia and often more actual spines subtending them. Current treatment of this species includes 12 varieties to cover all the different variants found in the polygona complex. Our plants are from cuttings taken off large specimens received with the plant collection of Stockton, California succulent grower Alice Waidhofer in 2005.
This information about Euphorbia polygona displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.
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