Ontario Weeds: Petty spurge

Table of Contents

1. Name
2. Other Names
3. Family
4. General Description
   • Photos and Pictures
5. Stems and Roots
6. Flowers and Fruit
7. Habitat
8. Similar Species
9. Related Links

Name: Petty spurge, Euphorbia peplus L.,

Other Names: euphorbe peplus, euphorbe des jardins

Family: Spurge Family (Euphorbiaceae)

General Description: Annual, reproducing only by seed.

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Photos and Pictures

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Stems & Roots: Stems erect, 10-30cm (4-12in.), single or branched from the base; top of each main stem 3-branched at base of inflorescence; lower and middle stem leaves alternate (1 per node), oblong to rounded, 1-2cm (2/5-4/5in.) long, short-stalked; leaves at tip of stem in one whorl of 3 leaves from the same node; leaves opposite (2 per node) in the inflorescence.

Flowers & Fruit: Inflorescence beginning as a 3-branched umbel and branching repeatedly in 2's, with a small flower cluster, in the angle between each pair of branches; flowers complex in cyathia or tiny cups, like those described for Leafy spurge; seedpods 3-lobed, containing 3 seeds; seeds about 1.5mm (1/16in.) long and about half as wide, somewhat 6-sided, the 2 inner faces with long, narrow depressions, the 4 outer surfaces with 2 to 4 circular depressions, gray to gray-brown. All parts contain a white milky juice which freely exudes when the plant is cut or broken. Flowers from early July until end of fall.

Habitat: Petty spurge occurs throughout southern Ontario in gardens, waste areas, roadsides and occasionally in cultivated fields.

Similar Species: It is distinguished from other erect-growing spurges by its annual habit, by the combination of alternate leaves on main stem, whorl of 3 leaves at tip of stem, and pairs of smaller opposite leaves in the inflorescence, by its main umbel at the tip of the stem having only 3 branches, and by its small, elongated, gray to brownish, 6-sided seeds with 2 elongated depressions and 4 rows of 2 to 4 rounded depressions. There is also a tendency for the stems to be somewhat succulent, and for the 3 main branches of the inflorescence to be somewhat enlarged above the nodes and taper upwards to be much thinner just below the next pair of small leaves.

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Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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