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Cirsium arizonicum - Arizona thistle

Scientific Family
Asteraceae
Synonyms
Cirsium nidulum, Cnicus arizonicus
Plant type
Forbs and Subshrubs
Origin
Native
Lifecycle
Biennial or perennial
Height
1 to 5 feet
Riparian
No
Stems 1 to several, erect or ascending, often hairy; flower head always appears partly open, bracts never allow it to spread into the typical wide disc shape of other thistles.
Stems woolly, erect, branching; cylindric flower heads of typically red (sometimes pink, orange, purple) disc flowers; spines of middle flower bracts shorter, inner bracts have elongated reddish tips; leaves are persistently densely hairy on underside.

Habitat

Variety of upland habitats, including desert scrub, grasslands, juniper woodlands, and openings in conifer forests.
Plant Community
Pinyon Juniper Woodlands
Montane Conifer Forest
Grasslands
Desert Scrub
Low elevation
3000
High elevation
9500

Flower Characteristics

As many as 100 flower heads per plant; each flower head, 5/8 to 2 inches long, made up of thin tubular disc flowers held tightly by layers of spiny bracts. The bracts have a central white line and are arranged in a tight spiral.
Flower color
Red to orange or pink to light purple
Flower shape
Daisy or dandelion-like
Tubular
No
First bloom month
May
Last bloom month
October
Flower clusters
None

Leaf and Stem Characteristics

Very hairy; basal leaves are 1-1/2 to 12 inches long and have spine-tipped teeth or lobes; stem leaves are usually clasping.
Leaf type
Simple
Leaf color
Grayish-green
Leaf shape
Triangular
Leaf margin
Toothed
Leaf attachment
Basal & Alternate
Leaves clasp
Yes
Leaf hairs
Leaves & stems
Spines
Yes

Fruit and Seed Characteristics

Smooth, compressed, 1/4 inch long, topped with plumose bristles.
Fruit type
Achene
Fruit color
Brown
Produces seeds that are an important food source for birds, especially for Northern Cardinals and Lesser Goldfinches.