Malta Starthistle

Information

Centaurea Melitensis - Asteraceae Family

malta_starthistle_1_tile malta_starthistle_2_tile malta_starthistle_3_tile malta_starthistle_4_tile

Identification

Flowers: The flowers are yellow, span up to 1.5 inches, and are surrounded by a ring of sharp tan spines.
Seeds: Seeds are tan with gray stripes. They are covered with fine hairs and have hooks to encourage spread by contact with other animals. Seeds can survive for up to 3 years in the soil.
Leaves: The leaves are alternate and narrowly oblong with smooth, toothed margins. They can be covered with stiff, thick hairs and resinous dots.
Flowering Time: Malta Starthistle flowers from May through September.
Life cycle: Malta Starthistle sprouts in late fall, remains a basal rosette through the winter, and in the spring grows 1-2 foot stems lined with spiny thorns. It flowers through the summer, producing seed in the fall.

Impacts

Malta Starthistle produces vigorous early growth and large mats that quickly displace other native species.
Due to its spiny thorns, Malta Starthistle can reduce an area’s potential for recreation.
Malta Starthistle has been implicated in the emergence of chewing disease, a neurological disease in horses.

Most effective control methods

Small infestations of Malta Starthistle can be effectively controlled by manually pulling and disposing in the trash prior to seed production.
Biological control is largely ineffective. It is a poor grazing plant due to its thorns and toxicity. Animals avoid it if possible.
When applied just before flower production, chemical control can be effective in controlling Malta Starthistle populations.

Malta starthistle: flower

Malta starthistle: rosette

Malta starthistle: flower

Malta starthistle: infestation

Malta starthistle: foliage

Malta starthistle: flowers

Malta starthistle: seeds

Malta starthistle: infestation