Centaurea melitensis – Maltese Star-thistle

Centaurea melitensis - Maltese Star-thistle, Tocolote, Tocalote, Spotted Knapweed, Malta Starthistle

Centaurea melitensis - Maltese Star-thistle, Tocolote, Tocalote, Spotted Knapweed, Malta Starthistle

Plant Name

Scientific Name: Centaurea melitensis

Common Names: Maltese Star-thistle, Tocolote, Tocalote, Spotted Knapweed, Malta Starthistle

Plant Characteristics

Duration: Annual, Biennial

Growth Habit: Herb/Forb

Arizona Native Status: Introduced

Habitat: Desert. This weed grows in disturbed areas, along roadsides, in fields, and in drainage ditches.

Flower Color: Yellow

Flowering Season: Spring

Height: To 3 feet (91 cm) tall

Description: The 1/2 inch (1.3 cm) wide flower heads are surrounded by spiny, cobwebbed bracts. The floral spines are tan-colored, 1/2 inch (1 cm) long, and have a reddish, pinnately spined base. These spines are painfully sharp and can cause injury to grazing animals if the plants are eaten. The upper leaves are linear, while the lower leaves are pinnately lobed.

The similar Yellow Star-thistle (Centaurea solstitialis) has longer, yellow spines.

Special Characteristics

Poisonous – This plant can be poisonous to horses.

Classification

Kingdom: Plantae – Plants
Subkingdom: Tracheobionta – Vascular plants
Superdivision: Spermatophyta – Seed plants
Division: Magnoliophyta – Flowering plants
Class: Magnoliopsida – Dicotyledons
Subclass: Asteridae
Order: Asterales
Family: Asteraceae – Aster family
Genus: Centaurea L. – knapweed
Species: Centaurea melitensis L. – Maltese star-thistle

More About This Plant

Arizona County Distribution Map