Purple Owl’s Clover

Purple Owl’s Clover © DSchiel

Exserted Indian Paintbrush
Castilleja exserta ssp. exserta

Description (Jepson, PlantID.net)

    • Eudicotyledon
      • Eudicots are a major lineage of flowering plants; see family for general characteristics
    • Broomrape Family (Orobanchaceae)
    • Annual herb, hemiparasitic
      • Densely hairy and glandular (sticky)
    • Leaves
      • Alternate (1 leaf at each junction with stem), with blades attached directly to the stem (sessile)
      • Linear, can be threadlike, usually with deeply-cut lobes
    • Flowers
      • Inflorescence (flower arrangement) is a dense spike (single stem bearing stalkless flowers)
      • Bracts (modified leaves at flower base) and sepals (usually green, outer flower parts) are lobed
        • Usually magenta with pink tips at Edgewood
      • Bilaterally-symmetrical flowers are usually white and magenta, with purple and yellow accents
        • Tube-shaped, partially covered by bracts and sepals
        • 5 fused petals in two sets
          • 2-lobed upper lip creates a hooked, very hairy beak (a slender projection)
          • 3-lobed lower lip forms a pouch with 2 dark spots
        • Stigma (pollen-receiving structure of the female flower) slightly exserted under the hook of the beak
      • Ovary superior (attached above other flower parts)
    • Fruit is a capsule (a dry, multi-chambered fruit that splits open at maturity)
    • Height to 18 in.


      • Native to California
        • Grows in grasslands
        • See Calflora for statewide observations of this plant
      • Outside California, grows in Arizona and New Mexico
      • Grows at elevations to 5,250 ft.

      Uses (Picking or removing any natural material from public land is illegal)

        • Host plant for the larvae of several butterfly species, including Leanira checkerspot (Chlosyne leanira), variable checkerspot (Euphydryas chalcedona), and the endangered Bay checkerspot (Euphydryas editha bayensis)
        • Native people harvested the seeds of owl’s clovers (Castilleja species), which were an important food source (Anderson 2005)
          • Flowers were used in ceremonial wreaths

        Name Derivation

          • Castilleja (kas-til-AY-ha) – named for Domingo Castillejo Muñoz (1744-1793), a Spanish surgeon and professor of botany
          • exserta (ex-SER-ta) – from the Latin meaning “protruding out or extending beyond,” probably referring to the slightly exserted stigma
          • Owl’s clover – flower’s lower lip pouch with 2 spots looks like an owl’s face, and the inflorescence roughly resembles that of some clover species
            • The Spanish Californians called owl’s clovers Escobitas, “little whisk brooms” (Bryant)


            • Partial root parasite (hemiparasitic)
              • Capable of photosynthesis, but obtains nutrients and water from a variety of other plants (Heckard 1962)
              • Specialized root structures called haustoria (singular, haustorium) penetrate the host plant’s roots
            • Colored bracts and sepals help attract pollinators
            • Edgewood’s purple owl’s clover is classified as a subspecies
              • Subspecies rank is used to recognize geographic distinctiveness, whereas variety rank is appropriate for variants seen throughout the geographic range of the species; in practice, these two ranks are not distinct
            • Known to hybridize with dense-flowered owl’s clover (C. densiflora)
            • Formerly in the Figwort family (Scrophulariaceae)

            ID Tips

              • May be confused with 3 other grassland Castilleja species at Edgewood: dense-flowered owl’s clover (C. densiflora ssp. densiflora), valley tassels (C. attenuata), and cream sacs (C. rubicundula ssp. lithospermoides)
                • Purple owl’s clover is the only one of these that has a hairy, hooked beak
              Dense-flowered Owl’s CloverPurple Owl’s CloverValley TasselsCream Sacs
              Hairinessslightly hairydensely hairy (cobwebby)slightly hairyhairy
              Inflorescencedense spikedense spikenarrow spikebulging spike
                 Sepal Colorgreen to pink

              light pink tips

              pink tips

              white or yellow tips

                 Petal Colormostly white with pink

              yellow and purple accents
              white and magenta or pink

              yellow and purple accents
              white to pale yellow

              yellow and purple accents

              bright yellow to cream
                 Pouch¹inflatedinflatedslightly inflatedgreatly inflated

              not hairy

              densely hairy

              not hairy

              not hairy
              ¹ Pouch: 3 lower fused petals
              ² Beak: 2 upper fused petals
              Dense-flowered Owl’s Clover (L), Purple Owl’s Clover (LM), Valley Tassels (RM), Cream Sacs (R)
              © DSchiel (L, LM, R), TCorelli (RM)
              Dense-flowered Owl’s Clover (L), Purple Owl’s Clover (LM), Valley Tassels (RM), Cream Sacs (R)
              © See Specific References

              At Edgewood

                • Found in grasslands
                • Flowers March – May

                See General References

                Specific References

                  Anderson, M.K. 2005. Tending the Wild. University of California, Berkeley.

                    Bryant, P.J. Castilleja exserta. Natural History of Orange County, California and Nearby Places.

                      Heckard, L.R. 1962. Root Parasitism in Castilleja. Botanical Gazette 124:1.

                        Mason, J. 2004. Owl’s clover beak [Illustration, adapted]. In T. Corelli, Flowering Plants of Edgewood Natural Preserve, 2nd. ed. Monocot Press, Half Moon Bay, California. (c) CC BY NC 3.0.

                          Miller, L.B. 2004. Castilleja attenuata, Castilleja densiflora ssp. densiflora, Castilleja exserta ssp. exserta, and Castilleja rubicundula ssp. lithospermoides [Illustrations]. In T. Corelli, Flowering Plants of Edgewood Natural Preserve, 2nd. ed. Monocot Press, Half Moon Bay, California. (c) CC BY NC 3.0.

                            Mitchell. M. 2017. Orobanchaceae-castilleja. Monterey County Wildflowers, Trees, & Ferns – A Photographic Guide.

                              Press, M.C. 1998. Dracula or Robin Hood? A Functional Role for Root Hemiparasites in Nutrient Poor Ecosystems. Oikos, 82:3, pp. 609-611.

                                Regents of the University of California. Castilleja exserta subsp. exserta. [illustration of beak, adapted] in Jepson Flora Project (eds.). Jepson eFlora.

                                  —–. Castilleja rubicundula subsp. lithospermoides. [illustration of beak, adapted] in Jepson Flora Project (eds.). Jepson eFlora.

                                    Shapiro, A.M. and Manolis, T.D. 2007. Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions. University of California Press, Berkeley – Los Angeles, California.