California Blackberry

Pacific Blackberry, Trailing Blackberry
Rubus ursinus
NATIVE

Description (Jepson, PlantID.net)

• Eudicotyledon
  • Eudicots are a major lineage of flowering plants; see family for general characteristics
• Rose Family (Rosaceae)
• Winter-deciduous perennial vine or shrub
• Stems with many sharp prickles (extensions of the epidermis)
• Leaves
  • Simple (not divided into leaflets) with 3 lobes or compound with 3 leaflets 
  • Coarsely toothed, with hair on underside
• Flowers
  • Inflorescence (flower arrangements) is a cyme (branched stem with flowers opening from the top down) of 1 to 5 white to pale-pink flowers
  • Male and female flowers usually on separate plants (dioecious)
    • Female flowers have smaller petals (~ 0.25 in.) and a central cluster of many pistils
    • Male flowers have larger petals (~ 0.5 in.) and a central cluster of many stamens
  • Hypanthium (floral cup formed from the fusion of petals, sepals, and stamens) is flat or saucer-shaped
  • Ovary superior (above the attachment of other flower parts)
• Berry is an aggregate fruit, a collection of small dark-purple fruits, called drupelets (small fleshy fruits with a hard seed)
• Height to ~6 ft.

Distribution

• Native to California
  • Grows in scrublands, woodlands, along streams, and in open or disturbed areas
  • See Calflora for statewide observations of this plant
• Outside California, grows from Canada south to Baja California, Mexico, and east to the Rocky Mountains
• Grows at elevations to 4,900 ft.

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

• Wildlife
  • Larval food source (host) for some butterflies, e.g. Western tiger swallowtail (Papilio rutulus), mourning cloak (Nymphalis antiopa), and gray hairstreak (Strymon melinus)
  • Deer browse the stems and foliage
  • Many animals, including birds, depend on the fruit as a food source
  • Many animals use the dense thickets for nesting sites and protective cover, including bees
• Native people
  • Berries were eaten fresh or dried, sometimes mixed with meat to form pemmican
  • Roots were made into a tea used to treat diarrhea
  • Leaves were also used to brew tea
  • Young shoots could be boiled and eaten
  • Bushes were actively managed by pruning and burning, stimulating many positive effects (Anderson 2005)
    • Vigorous and straighter shoots
    • Larger and more numerous fruits 
    • Less congested canopies
    • Reduced insect infestations 
    • Recycled nutrients

Name Derivation

• Rubus (ROO-bus) – from the Latin for “bramble” or “blackberry”
• ursinus (ur-SINE-us) – from the Latin for “bear-like”

Notes

• Pollinated by native bees
• Blackberries have prickles, rather than thorns or spines, which help deter herbivory
  • Prickles grow from the outer layers (epidermis) of plant stems, as on roses
  • True thorns are sharp-pointed modified stems, as on citrus trees and at Edgewood on chaparral pea (Pickeringia montana var. montana)
  • Spines are sharp-pointed modified leaves, as on cacti and at Edgewood on gooseberries, or leaf parts, as on leather oaks
• California blackberry is sometimes considered a “weed” as it can form dense populations along streams and ditches, out-competing other vegetation

ID Tips

• May be confused with non-native Himalayan blackberry (R. armeniacus) or poison oak (Toxicodendron diversilobum)
  • California blackberry has 3 small leaflets, green on both sides, and a round stem with many small straight prickles
  • Himalayan blackberry has 3-5 large leaflets with white undersides and a 5-angled stem with large, sharp, curved, and widely-spaced prickles (a more robust-looking plant)
  • Poison oak also has leaflets of three, but the leaves are not hairy
  • Mnemonic – “Leaves of three, let it be; If it’s shiny, watch your hiney; If it’s hairy, it’s a berry”

At Edgewood

• Found in moist areas and riparian woodlands
  • See iNaturalist for observations of this plant
• Flowers April – June
• Fruits in summer

See General References

Specific References

Anderson, M.K. 2005. Tending the Wild. University of California, Berkeley. Pp. 274-280.

Tirmenstein, D. 1989. Rubus ursinus. Fire Effects Information System. United States Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.

University of California Agriculture and Natural Resources (UC ANR). 2019. Wild blackberries. Statewide Integrated Pest Management Program.

Wilson, B. 2012. Rubus ursinus, Pacific Blackberry. Las Pilitas Native Plant Nursery.