Ontario Weeds: Plumeless Thistle
Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Other Names
- General Description
- Flowers and Fruit
- Similar Species
- Related Links
Name: Plumeless thistle, Carduus
Other Names: CRUAC, chardon épineux, Welted thistle
Family: Composite or Aster Family (Compositae)
General Description: Very similar to Nodding thistle with its deeply lobed, spiny leaves
Plumeleses thistle. A. Stand of plants
Plumeleses thistle. B. flower head.
Plumeless thistle. A. Rosette and lower stem leaves.
B. Flowering branch with flower heads on spiny-winged stalks.
Leaves: Distinguished from Nodding
thistle by usually having the lobes or clusters of lobes separated
from each other by distinct spaces along the midrib of the leaf.
The inner margins of these spaces usually with smaller and fewer
spines than on the lobes.
Flowers & Fruit: Flower heads smaller (usually less than 2.5cm, 1 in. wide) and clustered or sometimes solitary but on shorter stalks which are spiny-winged right to the base of the head. The incolucral bracts surrounding its flower heads are narrower and more numerous than in Nodding thistle and mostly point upward rater than outward or backward.
Habitat: Plumeless thistle occurs throughout southern Ontario in siliar habitats to Nodding thistle and, where the two occasionally grow in the same locality, hybride are often produced having characteristics intermediate between the two species.
Similar Species: Very similar to Nodding thistle.
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