Conopholis americana (American cancer-root)

Conopholis spp.

squawroot

Orobanchaceae

Eastern and southwestern North America and Mexico

Attracts Pollinators

Native to North America

SunFull Shade – Part Shade

WaterMedium

HardinessZones 4–8

Overview

Conopholis spp. is a genus of perennial root-parasitic plants in the broomrape family (Orobanchaceae), containing two species: C. americana of eastern North America and C. alpina of Mexico and the southwestern United States. The genus has no chlorophyll and draws all of its water and nutrients from the roots of host trees, mainly oaks, so plants live mostly underground and appear only when they flower. The emerging shoots are stout, unbranched, cone-like spikes 3 to 10 inches (8 to 25 cm) tall and 1 to 1.5 inches (2.5 to 4 cm) thick, clothed in overlapping yellow-brown scales rather than green leaves; a clump can carry several spikes 3 to 8 inches (8 to 20 cm) across. Tubular cream to pale yellow flowers open from the axils of the scales, each about 0.5 inch (12 mm) long, and are followed by capsules of dust-like seeds. Plants grow in the leaf litter of oak and oak-pine forests and cannot live apart from a host. Because they depend on established trees, they are not cultivated in the ordinary sense and are seen as wild components of mature woodland.

Native Range

Native to North America: C. americana ranges through eastern Canada and the eastern United States, and C. alpina occurs in the mountains of the southwestern United States and Mexico.

Suggested Uses

Encountered as a wild feature of oak woodland and native forest, of interest in naturalistic and conservation settings. The plants are not used in ordinary garden plantings because they depend on host tree roots.

How to Identify

Look for stout, unbranched, cone-like spikes pushing up through leaf litter under oaks, clothed in overlapping yellow-brown scales and lacking any green colour. The spikes resemble small upright pine cones. Tubular cream flowers open between the scales in spring.

Appearance

Size & Dimensions

Height3" - 10"

Width/Spread3" - 8"

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring

Flowering spikes emerge and bloom in spring, mainly April through June depending on latitude and elevation. The tubular cream to pale yellow flowers open from the base of the spike upward. After seed set the spikes blacken and wither, and the plant returns underground.

Detailed Descriptions

Flower Description

Cream to pale yellow

Foliage Description

Yellow-brown scales

Growing Conditions

Sun Requirements

SunFull Shade SunPartial Shade

Tolerates up to 3 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 Range5.0 - 7.0(Neutral)

357912

Soil Types

loam peat

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

Several years, dependent on host establishment

Care & Maintenance

Care Guide

Plants grow in the shaded, humus-rich leaf litter of oak and oak-pine forests, in soil with pH from 5.0 to 7.0. They are obligate root parasites and take their water and nutrients from host tree roots, so they cannot be grown without an established host. Hardiness spans roughly USDA zones 4 to 8. They appear in undisturbed woodland and do not transplant. No feeding or watering is involved in their care.

Pruning

No pruning is involved, as the plants are wild woodland parasites without persistent above-ground stems. The flowering spikes wither on their own after seeding. Surrounding leaf litter and host trees are left undisturbed.

✓ Toxicity

Non-toxic

Wildflower