Aphyllon uniflorum (one-flowered cancer-root)

Aphyllon spp.

broomrape

Native to North America

SunFull Sun – Part Shade

WaterLow

Overview

Aphyllon spp. is a genus of parasitic herbs in the broomrape family Orobanchaceae, native to North and South America and containing about 20 species once placed in Orobanche spp.. Plants lack chlorophyll and produce no true leaves, drawing all their water and nutrients from the roots of host plants to which they attach by swollen underground connections. The above-ground parts are fleshy flowering stems 2-12 inches (5-30 cm) tall, ranging from pale yellow and tan to purple or brown and clothed only in small scale-like bracts. Snapdragon-shaped flowers 0.4-1 inch (10-25 mm) long appear in spring and summer in shades of pale purple, lavender, yellow, or white, often with darker veins, borne singly or in clusters along the stem. Hosts vary by species and include members of the sunflower, stonecrop, and saxifrage families, among others; A. fasciculatum parasitizes sagebrush and buckwheat, while A. uniflorum attaches to a wide range of herbs. After flowering, each plant sets a capsule holding thousands of dust-like seeds that stay dormant in the soil until chemical signals from a suitable host root trigger germination. Because they depend entirely on their hosts, these plants appear only where their host species grow and cannot be cultivated apart from them.

Native Range

Native to North and South America, from Canada through the western United States and Mexico into the Andes. Plants occur wherever their host species grow, in habitats ranging from coastal scrub and sagebrush steppe to alpine slopes.

Suggested Uses

Aphyllon spp. is not a cultivated ornamental but is studied in native-plant and botanical settings as part of intact host communities. In natural areas it forms part of the local flora wherever its hosts occur. Several species are of interest in research on parasitic plants and seed germination.

How to Identify

Recognize Aphyllon spp. by its leafless, fleshy flowering stem in tan, yellow, purple, or brown, rising directly from the soil with no green foliage. The stem carries scale-like bracts and snapdragon-shaped flowers 0.4-1 inch (10-25 mm) long with five lobes and darker veining. The complete absence of chlorophyll and the attachment to a host root separate the genus from the green wildflowers it may grow among.

Appearance

Size & Dimensions

Height2" - 1'

Width/Spread2" - 6"

Colors

Flower Colors

purple

yellow

white

Bloom Information

Bloom Period

~4 weeks

Spring Summer

Flowering occurs in spring and summer, with timing set by the growth of the host plant. Each stem produces a succession of tubular flowers over several weeks. Capsules ripen soon after, releasing very large numbers of tiny seeds that can persist in the soil for years.

Detailed Descriptions

Flower Description

purple to yellow

Foliage Description

none; reduced to tan to purple scales

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 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 Range6.0 - 8.0(Neutral)

357912

Soil Types

loam sand rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Care & Maintenance

Care Guide

These plants are obligate root parasites and cannot be grown in ordinary garden soil or potting mix, since they require living roots of a specific host to survive. In the wild they appear in full sun to part shade wherever their hosts grow, across many soil types and a pH near 6.0 to 8.0. They draw water and nutrients entirely from the host, so they neither need nor respond to feeding or watering aimed at them. Reproduction occurs naturally when seed contacts a host root and germinates in response to its chemical signals. Heavy infestations can weaken crop or ornamental hosts. Most species are encountered as wild plants rather than cultivated ones.

Pruning

No pruning is practiced. The fleshy stems wither on their own once seed is shed and are not cut for shaping. Removing flowering stems before the capsules open can reduce seed spread where the genus is unwanted.