Chorizanthe spp.

spineflower

Polygonaceae Western North and South America

Attracts Pollinators Deer Resistant Drought Tolerant

Native to North America

Overview

Chorizanthe spp. is a genus of about fifty mostly annual herbs in the knotweed family, Polygonaceae, known as spineflowers and native to western North and South America, with a center of diversity in California and a second in Chile and Argentina. Plants are small and often prostrate to low-mounded, 1-12 inches (2.5-30 cm) across, with basal rosettes of small leaves and wiry, forking, reddish stems. The tiny flowers are enclosed in tubular involucres tipped with three to six teeth that end in straight or hooked spines or awns, giving the genus its common name and aiding seed dispersal by catching on fur and clothing. Flower color ranges from white and yellow to pink and rose. Many species grow on sandy or gravelly soils in coastal scrub, chaparral, and desert, and germinate after winter rain to flower and set seed within a single season. Several California species are highly localized, and a number are listed as threatened or endangered under state and federal law. One limitation is that the genus has little garden use and includes habitat-specialist annuals that are hard to grow away from their native soils. Most are warm-season annuals suited to zones 8-10.

Native Range

Chorizanthe spp. is native to western North America, especially California and the southwestern United States and Mexico, with a second group of species in temperate South America, mainly Chile and Argentina. Plants grow on sandy, gravelly, and disturbed open ground in coastal and arid habitats.

Suggested Uses

The genus is grown mainly in habitat restoration and the conservation of rare California species rather than for gardens. A few species appear in native seed mixes for sandy or coastal sites. Most are encountered in the wild rather than in cultivation.

How to Identify

Identify Chorizanthe spp. by its small size and wiry, often reddish, forking stems rising from a basal rosette. The defining feature is the tubular involucre around each tiny flower, tipped with three to six teeth ending in straight or hooked spines. Plants are typically low, dry, and prickly to the touch, with white, yellow, or pink flowers.

Appearance

Size & Dimensions

Height1" - 1'

Width/Spread2" - 1'

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Spring Summer

Flowering occurs from spring into summer, roughly April to July, after the winter rains in the genus's Mediterranean and desert climates. Annual species germinate, flower, and set seed within a few months. The spiny involucres persist on the dry stems after the seeds mature.

Detailed Descriptions

Flower Description

white, yellow, pink, or rose

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• 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

sand rocky loam

Drainagewell drained

Water & Climate

Water Needs

Low

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Most Chorizanthe spp. are not cultivated and grow only as wild annuals on open, sandy or gravelly ground in full sun. Where grown for conservation, plants need lean, sharply drained soil, full sun, and winter moisture followed by dry summers. They depend on a seasonal cycle of autumn or winter germination and resent rich soil or irrigation. The annual species die after setting seed and rely on the seed bank to return. The rare endemic species are hard to establish outside their exact native conditions. None need feeding.

Pruning

No pruning applies; the annual species die after flowering and seeding. Dead plants and their spiny involucres can be left to disperse seed or cleared once dry. No cutting back is involved in their growth.