Ontario Weeds: Petty spurge

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

  1. Name
  2. Other Names
  3. Family
  4. General Description
  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.

Photos and Pictures

Petty spurge

Petty spurge, inflorescence viewed from side.

Petty spurge, inflorescence viewed from side.
Petty spurge.

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.

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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