Synonyms:

Euphorbia greenwayi subsp. greenwayi

Habitat:

Euphorbia greenwayi is endemic to Iringa Escarpment, in Tanzania. It is extremely rare in the wild and has an area of occurrance of only 3 square kilometers! This place is located at an altitude between 1000 and 1250 meters above the sea level, where the plant grows in rocky outcrops in the Miombo woodland. It is threatened by habitat loss due to anthropic activities such as firewood. The extreme small area of occurrance and the habitat loss have resulted in this species being classified as critically endangered.

Description:

Euphorbia greenwayi is a succulent plant with slender stems that lie on the soil without putting roots on their way and reach a lenght of 30 meters. The stems form a tuft, spreading from the very base of the plant, at ground level, and are markedly four-angled, dark green-bluish, with darker blurs regularly arranged all along the crest, close to the spines. The 4 ribs are like lobated, with sharp tubercles at the spines. Spines and the edge of the crests show a strong, purple-red colour. The spines, instead are around 1 centimeter in length, slender and becoming black as they age.
The inflorescence, as in many Euphorbia, is a cyme: in this species, it is solitary and forked. The flowers are called cyathia, as in every Euphorbia. We remind that a cyathium (cyathia in the plural form) is one of the specialised false flowers forming the inflorescence of plants in the genus Euphorbia. In E. greenwayi they are short (up to 3 millimeters), pinkish, distinguished in male and female flowers. Male ones are fewer and deeply toothed, while female flowers are more reddish, longer (4 millimeters). Cyathia are enveloped by special structures that look like the petals of regular flowers, called cyathophylls, that, in this species, are cup-shaped and equipped with rectangular nectary glands.

Cultivation:

Euphorbia greenwayi is not difficult to grow. Here below are our tips:

Put it in a bright spot such as a sunny window. It can stay in a balcony in Spring and Summer, though you’ll have to increase gradually the sun exposure to prevent sunburns.
Keep it a temperatures above 5-8ºC. In theory, it could stand temperatures down to -1ºC, but we suggest to stay safe and place it indoors in Winter. Make sure its substrate stays completely dry during the Winter to avoid rotting.
Water in Spring and Summer, during the growth season, whenever the soil dries up up at its top inch (2,5 centimeters) before each irrigation. In Winter and Autumn, suspend watering.
Choose a very well-drained soil: a mix for succulents should do good. It has to have an abundant mineral part, made of pumice, clay or lapilli.
Fertilize once a year with a product rich in Phosphorus and Potassium and poor in Nitrogen. Dilute the product to half the doses recommended on the label. Never fertilize from September onwards: the stems might become fragile and too rich in water: a lush growth that might be fatal during the Winter.
Repot whenever the plant outgrows its pot. Euphorbia greenwayi will benefit from repotting, though it’s not necessary to repot every year. Repot in early Spring and choose pots that are only slightly larger than the diameter of the plant, like 1 or 2 centimeters wider. Wear gloves to protect from the irritating latex contained in its stem.

Propagation:

The easiest way to propagate this species is by cuttings.
Take off a cutting in Spring or Summer, wash it with warm water to remove the irritating latex, and lie it down in a gritty, porous compost to help the rooting. Sowing is also a possible method, though it’s more difficult to obtain success in germination.

Curiosity:

The latex of Euphorbias is often used in pharmaceutical industry because of its medicinal effects. The name of this species, “greenwayi”, has been chosen after the British botanist Dr. Percy J. Greenway, who worked in Tanzania frmo 1928 and in Kenya from 1957.

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