Castilleja rhexiifolia (Rhexia-leaved paintbrush)

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Castilleja, Genus, rhexiifolia, Species,

Genus & species

rhexia-leaved paintbrush

Orobanchaceae

Rocky Mountains and western North America

Attracts Pollinators Attracts Hummingbirds

SunFull Sun – Part Shade

WaterMedium

HardinessZones 3–7

Overview

Castilleja rhexiifolia is a herbaceous perennial in the broomrape family, native to the mountains of western North America. It grows 6-16 inches (15-40 cm) tall in clumps of unbranched stems. Like other paintbrushes it is hemiparasitic, tapping the roots of nearby grasses and other plants for part of its water and nutrients while still making its own food. The lance-shaped leaves are 1-2.5 inches (2.5-6 cm) long, sometimes with a few side lobes near the tip. The color near the top of each stem comes not from petals but from broad, rose-purple to crimson bracts that surround the small, greenish, tubular true flowers. Bloom comes in summer in mountain meadows and on slopes, often near or above treeline. The plant grows in moist subalpine and alpine meadows, open slopes, and streamsides at high elevation. Its dependence on host plants and on cool, high-elevation conditions makes it hard to grow in lowland gardens, and it is rarely transplanted with success.

Native Range

Castilleja rhexiifolia is native to the Rocky Mountains and ranges of western North America, from Alaska and western Canada south through the mountains of Montana, Wyoming, Colorado, and Utah. It grows in subalpine and alpine meadows and slopes.

Suggested Uses

Castilleja rhexiifolia is used in high-elevation native gardens, alpine and rock gardens, and mountain meadow restorations near host plants. Its rosy bracts add summer color to subalpine plantings. It draws hummingbirds and bees in its mountain range.

How to Identify

Look for a low clump 6-16 inches (15-40 cm) tall topped by broad rose-purple to crimson bracts, with small greenish tubular flowers tucked among them. The lance-shaped leaves may have a few narrow lobes near the tip. The rosy-purple bract color and high mountain meadow habitat separate it from the more orange and red lower-elevation paintbrushes.

Appearance

Size & Dimensions

Height6" - 1'4"

Width/Spread6" - 1'

Colors

Flower Colors

purple

red

pink

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~6 weeks

Flowers: June–August

Summer

The rose-purple to crimson bracts and small greenish flowers appear in summer (June-August), timed to the short high-mountain season. The colored bracts hold their display for several weeks, longer than the small true flowers last. Seeds ripen in capsules by late summer.

Detailed Descriptions

Flower Description

rose-purple to crimson bracts with greenish flowers

Foliage Description

green

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 Range6.0 - 7.5 (Neutral to alkaline)

3579

Soil Types

loam rocky sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Castilleja rhexiifolia grows in full sun to part shade in moist, gritty, well-drained mountain soils and needs cool summers and cold winters. As a hemiparasite it grows alongside host grasses and forbs whose roots it taps, and it is hard to establish without them. It is hardy in roughly USDA zones 3-7 and suited to high-elevation and northern gardens rather than hot lowlands. Sow seed in fall near suitable host plants, as the seed needs cold and a nearby host to establish. It resents transplanting and root disturbance. Warm, dry, low-elevation conditions are the main cause of failure.