Dense-flowered Owl’s-clover

Dense-flowered Owl’s-clover © DSchiel

Denseflower Indian Paintbrush
Castilleja densiflora ssp. densiflora
NATIVE – CA ENDEMIC

Description (Jepson, PlantID.net)

  • Eudicotyledon
    • Eudicots are a major lineage of flowering plants; see family for general characteristics
  • Broomrape Family (Orobanchaceae)
  • Annual herb, semi-parasitic
  • Leaves
    • Alternate (1 leaf at each junction with stem), with blades attached directly to the stem (sessile)
    • Linear- or lance-shaped, usually with deeply-cut lobes
  • Flowers
    • Inflorescence (flower arrangement) is a dense spike (single stem bearing stalkless flowers)
    • Bracts (modified leaves) at base of inflorescence and sepals (usually green, outer flower parts) are lobed and tipped white, pink, or purple
    • Bilaterally-symmetrical flowers are usually pink and white 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 straight beak (a slender projection), usually a darker color than the lower lip
        • 3-lobed lower lip forms a pouch with 2 dark spots
      • Stigma (pollen-receiving part of the pistil/female structure) exserted above the beak
    • Ovary superior (above the attachment of other flower parts)
  • Fruit is a capsule (a dry, multi-chambered fruit that splits open at maturity)
  • Height to 16 in.

Distribution

  • Native and endemic (limited) to California
    • Grows in grasslands
    • See Calflora for statewide observations of this plant
  • Grows at elevations to 5,250 ft.
Flower © LBMiller, JMason, LBMiller

Uses (San Mateo County Parks prohibits removal of any natural material)

  • Host plant for the larvae of several butterfly species, including Leanira checkerspot (Chlosyne leanira), variable checkerspot (Euphydryas chalcedona), and the endangered Bay checkerspot (E. 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
  • densiflora (den-si-FLOR-a) – from the Latin densa, “dense” and flores, “flowers,” meaning “densely flowered”
  • 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)

Notes

  • 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 dense-flowered 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 purple owl’s-clover (C. exserta ssp. exserta)
  • Formerly in the Figwort family (Scrophulariaceae)

ID Tips

Dense-flowered Owl’s-cloverPurple Owl’s-cloverValley TasselsYellow Cream Sacs
Hairinessslightly hairydensely hairy (cobwebby)slightly hairyhairy
Inflorescencedense spikedense spikenarrow spikebulging spike
Flower
   Sepal Colorgreen to pink

light pink tips
magenta

pink tips
green

white or yellow tips

green
   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
   Beak²straight

not hairy
hooked

densely hairy
straight

not hairy
straight

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), Yellow Cream Sacs (R)
© DSchiel (L, LM, R), TCorelli (RM)
Dense-flowered Owl’s-clover (L), Purple Owl’s-clover (LM), Valley Tassels (RM), Yellow Cream Sacs (R)
© See Specific References

At Edgewood

  • Found in serpentine and non-serpentine grasslands
    • See iNaturalist for observations of Castilleja densiflora
  • 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, adapted]. 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: Broomrape Family — Castilleja (Paintbrush & Owl’s-clover). 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.