Anisocarpus spp.

tarweed

Attracts Pollinators Drought Tolerant Fragrant (moderate)

Native to North America

SunFull Sun – Part Shade

Overview

Anisocarpus spp. is a small genus of two species of tarweeds in the daisy family, Asteraceae, native to western North America and segregated from the related genus Madia spp.. The genus includes both an annual and a woodland perennial, with slender, sparsely branched stems 8-40 in (20-100 cm) tall that are glandular and sticky toward the top and carry a strong resinous scent. The leaves are narrow and lance-shaped, mostly toward the stem base, and often clammy to the touch. From late spring into summer the stems bear small daisy-like flower heads with yellow ray florets, sometimes red-marked at the base, surrounding a yellow disc. The bracts around each head are studded with stalked glands. A. madioides, woodland tarweed, is a slender perennial of shaded forest and woodland edges, while A. scabridus is a rough annual of open mountain slopes. The flower heads close in strong midday sun and open toward evening. Anisocarpus spp. sets seed and, in the annual, dies within one season; the sticky foliage can collect dust and small debris.

Native Range

Anisocarpus spp. is native to western North America, with A. madioides ranging through the coastal mountains and forests from British Columbia to California, and A. scabridus restricted to higher elevations in the Klamath and Cascade ranges.

Suggested Uses

Anisocarpus spp. is grown in native-plant gardens, woodland edges, and naturalistic meadow plantings in its home region, where the summer flowers draw native bees and other pollinators. The seeds feed small birds. The resinous, sticky foliage limits its use in high-traffic or formal plantings.

How to Identify

Recognise Anisocarpus spp. by its sticky, glandular, resin-scented stems and narrow leaves, and its small yellow daisy heads carried on slender stalks in summer. Stalked glands cover the bracts that enclose each head, and the seed-bearing ray florets sit within folded bracts, a feature shared with other tarweeds. Its sticky herbage and forest or mountain habitat separate it from the open-ground Madia spp. species.

Appearance

Size & Dimensions

Height8" - 3'4"

Colors

Flower Colors

yellow

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

Spring Summer

Flowering runs from late spring into late summer (roughly May-August in the Northern Hemisphere), with the small yellow heads opening over many weeks. The flowers tend to open in the cooler parts of the day and close under intense midday sun. Seed follows through summer and autumn, and the annual species relies on this seed to return the next year.

Detailed Descriptions

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

loam rocky sand

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Across the genus, Anisocarpus spp. grows in well-drained soils in sun to partial shade, with the perennial woodland tarweed favouring dappled shade and leaf-littered ground and the annual taking open, rocky, sunnier sites. Both tolerate summer drought, drawing on the dry-season conditions of their native range, and do poorly in heavy, wet soils in winter. Plants are rarely cultivated and are grown mainly in native-plant and habitat gardens from seed sown in autumn or spring. Little feeding is needed, and lean soils suit the genus. The sticky, scented foliage deters some browsing animals.

Pruning

No pruning is needed for these herbaceous tarweeds. Spent stems of the perennial can be cut back after flowering, and the annual is left to set and shed seed before it dies. Removing seed heads early limits self-sowing where it is not wanted.