Hairy Bittercress

Pop Seed
Cardamine hirsuta
NON-NATIVE

Description (Jepson, PlantID.net)

• Eudicotyledon
  • Eudicots are a major lineage of flowering plants; see family for general characteristics
• Mustard Family (Brassicaceae)
• Annual herb
  • Lower part of plant hairy
• Leaves
  • Form a basal rosette and occur along the stem
  • Each leaf is divided into 4-7 leaflet pairs (pinnately compound) with a larger terminal leaflet
• Flowers
  • Inflorescence (flower arrangement) is a raceme (unbranched, elongated flower cluster with short, equal stalks; bottom flowers open first)
  • White, with 4 petals, sometimes absent
    • Usually 4 stamens (male flower parts)
  • Ovary superior (above the attachment of other flower parts)
• Fruit is a silique (long, narrow pod), appressed to the stem, that dehisces (splits open)
  • 2 sides of the mature pod will coil back explosively, scattering seed up to several feet
• Height to 14 in.

Distribution

• Non-native to California
  • Grows in shady, damp areas
  • See Calflora for statewide observations of this plant
• Native to Europe and Asia
  • Introduced world-wide
• Grows at elevations to 2,625 ft.

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

• Wildlife
  • Larval food source (host) for Sara orangetip (Anthocharis sara), cabbage white (Pieris napi) and echo blue (Celastrina ladon echo) butterflies
  • Nectar source for cabbage white butterfly (Pieris napi)
  • Nectar and pollen source for bees
• Human
  • Leaves may be eaten raw or cooked

Name Derivation

• Cardamine (kar-DAM-ih-nee) – from the Greek kardamis, “a kind of cress,” referring to an East-Indian spice
• hirsuta (her-SOO-ta) – from Latin for “covered with hairs”
• Bittercress – this edible herb has a mild peppery taste

Notes

• Naturalized plant, which although non-native, reproduces and maintains its population without human cultivation
  • Non-native describes plants that have been introduced by deliberate or accidental means from other regions or countries
• Plant has a 12-week life cycle, producing up to 1,000 seeds, thus can quickly become invasive (NC Extension)
• If you come across a bittercress with mature, dry seed pods, run your hand over the plant to experience just how explosively the seeds are expelled
  • The explosive release of seeds from a pod is called ballochory
• Herbarium specimens have been misidentified as the native few-seeded bittercress (C. oligosperma) due to several common features

ID Tips

• Maybe be confused with California mustard (Caulanthus lasiophyllus), which has similar small white flowers
  • Hairy bittercress
    • Height ranges from 4 to 14 in.
    • Basal leaves are pinnately compound, with rounded leaflets
  • California mustard
    • Height ranges from 8 in. to over 5 ft.
    • Basal leaves are lobed or toothed, like a dandelion leaf
• May be confused with the rarely-seen, native few-seeded bittercress (C. oligosperma)
  • Hairy bittercress
    • Fruits are erect and usually appressed to the stem
    • Usually 4 stamens
    • Seeds have margins
  • Few-seeded bittercress
    • Fruits have a more spreading habit and are usually not appressed to the stem
    • 6 stamens
    • Seeds lack margins

At Edgewood

• Found in woodlands
  • See iNaturalist for observations of this plant
• Flowers February – June

See General References

Specific References

North Carolina Extension Gardener Plant Toolbox. Cardamine hirsuta. North Carolina State University Cooperative Extension.

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