Natives For Your Neighborhood
Conservation of rare plants, animals, and ecosystems

General Landscape Uses: Primarily recommended for natural landscapes and habitat restorations. Also wildflower and butterfly gardens.

Ecological Restoration Notes: A rather frequent understory of pinelands and prairies.

Availability: Grown by enthusiasts and occasionally by native plant nurseries.

Description: Medium wildflower with prickly leaves.

Dimensions: Typically 12-18 inches in height; 3 feet or more when in flower. The basal rosette is broader than tall.

Growth Rate: Moderate.

Range: Eastern United States west to Texas and south to the Monroe County Keys; West Indies (Bahamas), southern Mexico and Central America. In the Monroe County Keys, disjunct from Miami-Dade County to the pine rocklands of Big Pine Key.

 Map of select IRC data from peninsular Florida.

 Map of suggested ZIP codes from South Florida north to southern Brevard, Osceola, Polk, and Pasco counties.

 Map of ZIP codes with habitat recommendations from the Monroe County Keys north to Martin and Charlotte counties.

Habitats: Pinelands and prairies.

Soils: Moist, well-drained to moderately well-drained sandy or limestone soils, without humus.

Nutritional Requirements: Low; it grows in nutrient poor soils.

Salt Water Tolerance: Low; does not tolerate long-term flooding by salt or brackish water.

Salt Wind Tolerance: Moderate; grows near salt water, but is protected from direct salt spray by other vegetation.

Drought Tolerance: High; does not require any supplemental water once established.

Light Requirements: Full sun.

Flower Color: Purple to lavender, pink or white.

Flower Characteristics: Showy flowering heads 2-3" in diameter.

Flowering Season: All year; peak spring-fall.

Fruit: Inconspicuous achene.

Wildlife and Ecology: Larval host plant for little metalmark (Calephelis virginiensis) and painted lady (Vanessa cardui) butterflies. Nectar plant for black swallowtail (Papilio polyxenes), Delaware skipper (Anatrytone logan), palamedes swallowtail (Papilio palamedes), palmetto skipper (Euphyes arpa), three-spotted skipper (Cymaenes tripunctus), twin-spot skipper (Oligorio maculata) and other butterflies. The flowers also attracts bees, wasps, beetles and other insects, and hummingbirds. Birds eat the seeds.

Horticultural Notes: Can be grown from seed.

References: Hammer 2004

Comments: The name "horridulum" refers to the very prickly leaves. This is a major attractor of insect pollinators. The flowering heads are often torn apart by beetles. See also the Florida Wildflower Foundation's Flower Friday page and Xerces Society's Native Thistles: A Conservation Practinioner's Guide (Eckberg et. al 2017).