Annual Spurges
What are they?
The spurges are a rather large group of plants in the family Euphorbiaceae. This is a rather variable group of plants that includes creeping, ground-hugging annuals, rather weedy species of open ground and a varied bunch of multi-stemmed perennials which typically have rather stiff, upright stems; this page covers the annual species that are mostly relatively small and well-branched. The spurges mostly have green or yellowish-green flowers that are made up of an intriguing and highly distinctive cluster of parts. These parts typically include a female flower and a small cluster (perhaps 2-4) of male flowers. These flowers sit atop a small structure (technically called a cyathium) which also carries a ring of yellowish or reddish, often glistening, glands. The glands are more or less semi-circular in outline, but the outer tips of the semi-circles are often drawn out into a pair of narrow extensions like little cow horns. After pollination, the stalked, female ovary elongates and becomes enlarged as the seeds develop inside.
Where are they found?
These annual plants are typically found as weeds or adventives on open ground, either where disturbed by cultivation - such as arable fields, gardens or allotments - or on gravel paths and tracks, in pavement cracks and similar places.
Identification
All species can be quickly identified as spurges by their milky snap, which is revealed by pulling off part of a leaf. A quick look at leaf shape is a good first step to narrow down the choices. After that, identification is largely based upon the flower structure and you should note the colour of the flowers (especially the glands) and the number and shape of the glands. After flowering, details of the fruit should be noted, especially whether the surface of the seed pod is smooth or bumpy and hairless or hairy.
Petty Spurge Euphorbia peplus
An ancient introduction. Common and widespread throughout East Anglia, especially as a weed of gardens, paths and urban areas in general. Flowers late March to November. Slender stemmed and much branched to 40cm in height and often forming coloniers of many plants. Leaves and flower bracts soft and broad, with smooth, untoothed margins. Flowers tiny with green glands which have long, horn-like extensions. Seed capsules three-sided, each with two, winged ridges.
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Sun Spurge Euphorbia helioscopia
An ancient introduction. Common and widespread throughout East Anglia, as an arable weed and as a weed of gardens, paths and urban areas. Flowers late April to October. Main stem typically unbranched to 50cm in height with a branched flowerhead. Leaves and flower bracts with toothed margins towards their tips. Flowers tiny with oval to kidney-shaped, green glands which have no horn-like extensions. Seed capsules three-sided, smooth and unridged on their surfaces.
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Upright Spurge Euphorbia stricta
Introduced as a garden plant in East Anglia, though thought by some to perhaps be native in western Britain. Rare; recorded from two places in Suffolk in the county atlas and recently found beside a footpath in Norfolk. Flowers June to August. A rather frail, annual or biennial species, growing to 80cm in height. Leaves lightly saw-toothed along the margins, 1-6cm in length. Flower bracts bright yellow, broadly rounded with pointed tips. Flower glands yellow, rounded and without projections. Seed capsules covered in tubular bumps called papillae.
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Dwarf Spurge Euphorbia exigua
An ancient introduction. Uncommon and declining but still quite widespread in arable fields, especially on the boulder clay. Flowers June to October. A small, slender species to 30cm in height, usually branching from low down. Leaves linear, flower bracts long-pointed. Flowers tiny with oval to kidney-shaped, golden-brown glands which have long, horn-like extensions. Seed capsules three-sided, smooth and unridged on their surfaces.
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