Ontario Weeds: Creeping yellow cress

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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. Leaves
  7. Flowers and Fruit
  8. Habitat
  9. Similar Species
  10. Related Links

Name: Creeping yellow cress, Rorippa sylvestris (L.) Bess.,

Other Names: rorippe sylvestre

Family: Mustard Family (Cruciferae

General Description: Perennial, reproducing by rhizomes and by seed.

Photos and Pictures

Creeping yellow cress.
Creeping yellow cress. A. Three shoots arising form a spreading underground rhizomes and showing a rosette of basal leaves formed at ground level on one of those shoots. B. Top of flowering stem.
Creeping yellow cress. A. Three shoots arising form a spreading underground rhizomes and showing a rosette of basal leaves formed at ground level on one of those shoots. B. Top of flowering stem.

Stems & Roots: Spreading or ascending 10-60cm (4-24in.) high, simple to freely branched;

Leaves: Thin and pinnately parted almost to midrib, lanceolate in outline, with toothed or cut divisions that are lanceolate or linear; lower leaves up to 20cm (8in.) long, upper ones progressively reduced;

Flowers & Fruit: Flowers in small clusters at ends of branches; the clusters expanding into elongated, open racemes as the flowers mature; each flower 3-10mm (1/8-2/5in.) wide, with 4 bright yellow petals longer than the 4 sepals; seedpods (siliques) slenderly linear-cylindric, 2-15mm (1/12-3/5in.) long and 0.4-1.5mm (1/50-1/16in.) wide; their pedicels 3-20mm (1/8-4/5in.) long, thread-like and spreading perpendicular to the stem; seeds 0.6-0.8mm (1/40-1/30in.) long. Many patches of Creeping yellow cress do not set seed and their seedpods remain undeveloped. Flowers from June to September.

Habitat: Creeping yellow cress was introduced from Eurasia and is found throughout southern Ontario in moist soil in river beds, along sand dunes, wet meadows and in depressional areas in fields and gardens.

Similar Species: It is distinguished by its perennial habit of growth often resulting in dense patches with numerous intertwining rhizomes, its petals being much longer than its sepals, its lateral leaf segments often being sharply toothed and more widely spaced than in Marsh yellow cress, and the frequent absence of seed set.

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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