Scientific Family
Asteraceae
Synonyms
Centaurea stoebe ssp. micranthus, Acosta maculosa, Centaurea maculosa
Plant type
Forbs and Subshrubs
Origin
Introduced
Lifecycle
Biennial or perennial
Similar species
Centaurea diffusa
Height
8 inches to 4 feet
Riparian
No
This invasive plant grows from a basal rosette in its first year into a bushy plant in its second year, blossoming with a profusion of small flowers for months and generating new rosettes for future growth.
Spotted knapweed is distinguished reliably by its "spots" or blackened bract ends. Pink to purple disc flowers only. Leaves divided into very narrow lobes, grayish-green.
Habitat
It prefers dry, coarsely textured soils that drain well, especially in south facing locations. It readily invades disturbed sites, choking out native vegetation, once established, it moves into surrounding more pristine areas.
Plant Community
Disturbed Areas
Low elevation
1900
High elevation
10000
Flower Characteristics
The flower can be 3/4 to 1 inch wide and when fully open is disc-like. The flower emerges from a cone of bracts, which distinguish the plant with their black tips and coarse bristles.
Flower color
Pink to purple, rarely white
Flower shape
Daisy or dandelion-like
Tubular
No
First bloom month
June
Last bloom month
October
Flower clusters
None
Leaf and Stem Characteristics
Erect, wiry stems that are green or gray in color branch freely at mid-height, producing 15 or more flowering stems. Leaves, which may be 6 inches long near the stem, are dotted with resin, narrow and deeply lobed, lobes are toothed at their end.
Leaf type
Simple
Leaf color
Gray green to dark green
Leaf shape
Pinnatifid
Leaf margin
Toothed
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
No
Fruit and Seed Characteristics
Fruit type
Achene
Fruit color
Brown to black
Seeds are oval with pale lengthwise lines and short fringe on one end.