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Purple Owl's Clover
Castilleja exserta
About Purple Owl's Clover (Castilleja exserta) Nurseries Show All Photos Owl's Clover is a species in the Orobanchaceae (Broomrape) family. The genus Castilleja, which includes the Indian paintbrushes, includes numerous species. It was formerly included in the genus Orthocarpus, and some sources may still refer to it by that name. This species is native to the southwestern United States but may be found in places where it has been introduced, such as Hawaii. In California there are three recognized subspecies with fairly distinct geographical ranges. The plant is an annual about a foot tall with a hairy stem covered in thready leaves. Although this species is variable in appearance and easily hybridizes with other Castilleja, it generally bears a brightly-colored flower cluster of shaggy pink-purple or lavender flowers that resemble clover (but they are not related). The thin, erect leaves are usually tipped with the same color, giving the flower cluster the appearance of a paintbrush. It produces pods containing seeds.

Like other related plants in the family, this is a hemiparasite which derives some of its nutrients directly from the roots of other plants by injecting them with haustoria; this is the reason for its small, reduced leaves. Therefore, it is almost always planted with a perennial species to serve as the host plant.
Plant Description
Plant Type
Annual Herb

Max. Height
1.5 ft (0.46 m)

Max. Width
1 ft (0.3 m)

Flower Color
Lavender, Pink, Purple

Flowering Season

Native Status

Natural Setting
Site Type
Grasslands and openings in chaparral or woodlands; occasionally in desert areas


Elevation ?
-73' - 11310'

Annual Precip. ?
3.4" - 68.1"

Summer Precip. ?
0.13" - 2.98"

Coldest Month ?
24.6° F - 58.8° F

Hottest Month ?
45.5° F - 87.5° F

Humidity ?
0.19 vpd - 38.31 vpd

Soil Description
Tolerant of sand and clay

Soil PH
5.0 - 8.0

Fast, Medium, Slow

Cold Tolerance(° F)
Tolerates cold to 15° F

Companion Plants
Use in a meadow-like planting with other annuals such as Clarkis sp., California Poppy (Eschscholzia californica), Baby Blue-eyes (Nemophila menziesii), and Lupine (Lupinus sp.); also with geophytes such as Wild Onions (Allium sp.), Ithuriels's Spear (Triteleia laxa), Blue Dicks (Dichelostemma capitatum), and Mariposa Lily (Calochortus sp.).

Wildlife Attracted
The flowers attract bees and butterflies. This is a crucial host plant for the Bay Checkerspot butterfly, a threatened species in California. The Castilleja genus is beneficial for the Leanira Checkerspot and Chalcedon Checkerspot butterflies.

Landscaping Information
Ease of Care
Moderately Easy

Water Requirement ?
Very Low, Low
Extremely Low
Very Low
Moderate - High

Seldom Used

Propagation ?
By seed. It must be planted with a perennial host plant such as a native grass (Stipa or other species).

Common uses
Butterfly Gardens, Bee Gardens

Nursery Availability
Commonly Available

Other Names
Botanical Names
Orthocarpus purpurascens

Common Names
Exserted Indian Paintbrush

Sources include: Wikipedia. All text shown in the "About" section of these pages is available under the Creative Commons Attribution-ShareAlike License. Plant observation data provided by the participants of the California Consortia of Herbaria, Sunset information provided by Jepson Flora Project. Propogation from seed information provided by the Santa Barbara Botanical Garden from "Seed Propagation of Native California Plants" by Dara E. Emery. Sources of plant photos include CalPhotos, Wikimedia Commons, and independent plant photographers who have agreed to share their images with Calscape. Other general sources of information include Calflora, CNPS Manual of Vegetation Online, Jepson Flora Project, Las Pilitas, Theodore Payne, Tree of Life, The Xerces Society, and information provided by CNPS volunteer editors, with special thanks to Don Rideout. Climate data used in creation of plant range maps is from PRISM Climate Group, Oregon State University, using 30 year (1981-2010) annual "normals" at an 800 meter spatial resolution.

Links:   Jepson eFlora Taxon Page  CalPhotos  Wikipedia  Calflora

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