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Centaurea melitensis - Maltese star-thistle

Scientific Family
Asteraceae
Other common names
Malta starthistle
spotted knapweed
Plant type
Forbs and Subshrubs
Origin
Introduced
Lifecycle
Biennial or annual
Similar species
Centaurea solstitialis
Height
2 to 3 feet
Riparian
Yes

The winged stem is stiff, openly branched and covered with cottony short soft hairs.

Flower heads of 1/2 to 1 inch, usually on stems, not concealed by foliar bracts, spine tipped phyllaries (bracts) , spines under 1/2 inch long and phyllary appendages that are spiny fringed distinguish this from other Centaurea sp.

Habitat

This starthistle prefers disturbed and open areas, including grasslands, woodlands, agricultural fields, and roadsides.

Plant Community
Desert Scrub
Disturbed Areas
Grasslands
Interior Chaparral
Montane Conifer Forest
Pinyon Juniper Woodlands
Riparian
Low elevation
0
High elevation
7200

Flower Characteristics

Flower heads are surrounded by sharp, straw-colored 3/4 inch thorns. One to few flower heads at branch tips are borne singly or in open arrays.

Flower color
Yellow
Flower shape
Daisy or dandelion-like
Tubular
No
First bloom month
April
Last bloom month
July
Flower clusters
None

Leaf and Stem Characteristics

Basal leaves are deeply lobed, while the upper leaves are entire and sharply pointed. Leaves are resin dotted. Margins of the leaves can be smooth, toothed, or wavy depending on the individual plant and its maturity.

Leaf type
Simple
Leaf color
Gray-green
Leaf shape
Narrow
Leaf margin
Lobed
Leaf attachment
Basal & Alternate
Leaves clasp
No
Leaf hairs
Leaves & stems
Spines
No

Fruit and Seed Characteristics

Fruit type
Achene
Fruit color
Light brown

Seed production is highly variable from year to year and plant to plant.