Nomenclature

Species name:

Euphorbia helioscopia   L.

Author(s):

Carl von Linné
   Sweden, 1707-1778

General names:

Sun Spurge, Sun euphorbia,
Madwoman's Milk,
Wart spurge, Wart weed, Wart grass,
Cat's milk,
Umbrella milkweed

Maltese name:

Tengħud Raddiena

Plant Family:

Euphorbiaceae   (Spurge Family)

Name Derivation:

Euphorbia = Named for Euphorbus, a Greek physician to Juba II, King of Mauretania. Euphorbus derives from eu, "good," and phorbe, "pasture or fodder," thus giving euphorbos the meaning "well fed." (Greek);

Helioscopia = From the Greek helios (sun), referring to the habit of the flower heads turning towards the sun (Greek).

Synonyms:

Euphorbia lunulata, Euphorbia dominii, Tithymalus helioscopius, Galarhoeus helioscopius

Plant Description

Life Cycle:

Annual

Habitat:

In waste and cultivated places, sometimes cosmopolitan.

Source in Malta:

Quite common throughoutt the Maltese islands.

Plant Height:

Up to 50cm in height.

Flowering Time:

Nov - May

This is a common weed of disturbed habitats and gardens. It is a hairless, erect annual that may reach up to 50cm in height. It usually has simple green stems that usually do not branch (occassionally the stem branches from the base).

The Leaves are variable in shape and occur alternately on the stem. They may be oval in shape to spoon-shaped (spathulate). They have tiny teeth at their margin but end in a blunt point. They are soft to touch and bright green in colour and may reach up to 5cm in diameter. They easily release a white milky substance when cut typical of Euphorbial species. The leaves underneath the inflorescence (the Ray leaves) are similar in shape to the upper cauline leaves but are usually smaller but are usually grouped together above which the stem divides.

This plant is monoecious (both male and female flowers are on the same plant). The flowers lack petals and are borne in Umbel clusters (inflorescence of many flowers on different pedicels that originate from the same point). These umbel clusters are called Rays. Below these Rays are the Ray leaves, and these Rays end forming the Cyathium. There are usually 5 Rays in this species, and the Rays first divide in threes (Trichotomous branching) and then divide in twos (Dichotomous branching). Along the Rays (especially when the Rays branch) lie the Raylet leaves which are oval to spathulate in shape and have a toothed margin. They clasp the stem and the base of the Cyathium. They have a smooth outline.

The Cyathium consists of 2 bracts that have a similar shape to the Raylet leaves but usually end with a pointed but blunt tip. Over them lie the male and female flowers. The male flowers are tiny and consist of a single stamen and lie over the gland. The gland is green and jelly-like in colour and is smooth in outline with the shape of a square 8. The female flower is larger and is a round structure with the shape of a pea and is up to 5mm in diameter and is green in colour. It has styles coming out of its apex.

The capsule is up to 4mm in size and is deeply notched in shape. The seeds are up to 2mm in size and are oval in shape and are dark-brown in colour and have a wrinkled shape.

In the Maltese islands it is difficult to confuse this species with anything else. It is the only annual Euphorbial species that has smooth glands and lacks stipules. Another European closely related species include Euphorbia phymatosperma that has entire leaves and seeds having 3 depressions, but this species is absent from our islands.

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