Buchnera spp.

bluehearts

Orobanchaceae

Tropical and warm-temperate worldwide

Attracts Pollinators Attracts Butterflies

Native to North America

SunFull Sun – Part Shade

WaterMedium

HardinessZones 5–9

Overview

Buchnera spp. is a genus of about 100 species of slender, hemiparasitic herbs in the broomrape family (Orobanchaceae), found across tropical and warm-temperate regions worldwide and known as bluehearts. The plants are partial root parasites: they make their own food by photosynthesis but tap the roots of neighbouring grasses and other plants for water and minerals. From a rough, often bristly stem 12 to 36 inches (30 to 90 cm) tall rise narrow, opposite leaves and a terminal spike of small tubular flowers. The flowers are typically blue to violet, sometimes white, about 0.4 to 0.6 inch (10 to 15 mm) across, with five spreading lobes. Most parts blacken as they dry, a feature shared across the genus. Buchnera spp. grows in prairies, savannas, open pine woods, and seasonally moist grassland, depending on suitable host plants nearby. Flowering occurs through summer into autumn. Because of the parasitic root habit, the genus is difficult to grow away from its natural plant community and is rarely cultivated.

Native Range

Buchnera spp. is widespread across the tropics and warm-temperate zones of the Americas, Africa, Asia, and Australia. B. americana, American bluehearts, is native to the central and eastern United States, growing in prairies, savannas, and open woodland.

Suggested Uses

Grown mainly in prairie restorations, savanna plantings, and native grassland gardens alongside its host grasses, rather than as a stand-alone ornamental. The blue flower spikes add vertical colour among warm-season grasses. It suits naturalistic plant communities where host species are present.

How to Identify

Identify Buchnera spp. by its slender, rough-haired stems, narrow opposite leaves, and a terminal spike of small five-lobed tubular flowers in blue to violet. A reliable clue is that the leaves and stems turn black as they dry. Its hemiparasitic habit and blackening tissue separate it from similar spike-flowered prairie herbs.

Appearance

Size & Dimensions

Height1' - 3'

Width/Spread6" - 1'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Summer Fall

Flowering runs through summer and into autumn, roughly June to September, with flowers opening a few at a time up the spike. The small tubular flowers are blue to violet, occasionally white. Bloom can continue for many weeks where moisture and host plants are available.

Detailed Descriptions

Flower Description

blue to violet

Foliage Description

green, blackening when dry

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 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 Range5.0 - 7.0(Neutral)

357912

Soil Types

loam sand

Drainageaverage

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Buchnera spp. grows in full sun on moderately moist, well-drained soils with a pH of 5.0 to 7.0, and requires living host plants, usually grasses, whose roots it taps for water and nutrients. It cannot be grown like an ordinary perennial, as seedlings establish only where suitable hosts are present, which makes deliberate cultivation difficult. In a prairie or savanna planting it persists naturally among its host community. Excess fertiliser and disturbance of the host grasses both reduce its success. It tolerates seasonal dryness once the host system is established.

Pruning

No routine pruning is needed. Spent flowering spikes can be left to set and shed seed within the planting. Cutting back the surrounding grasses too hard removes the hosts the plant depends on.

⚠️ Toxicity Warning

Unknown

Perennial