Cercis – from kerkis (Greek), meaning weaver’s shuttle, in reference to the resemblance of each seed pod to a weaver’s shuttle

Native range: N. America, Europe, Asia

Leaves:

• alternate
• simple
• palmately veined, entire
• orbicular to cordate
• cordate to truncate base
• blunt apex
• leaves appear after the flowers

Flowers:

• umbel-like clusters or racemes before leaves emerge
• perfect
• 5 sepals, fused forming cup-like calyx
• papilionaceous flowers:
  • 5 petals
    • 2-lipped (larger), covering stamens and ovary
    • 3 upper curved back
  • 10 stamens
• deep pink, purple-red, white bloom on year old or older wood, including the trunk
• any one shrub will be in flower for only ~2 weeks, though flowering period is longer at the population level

Fruit:

• long, flat, thin pendulous pods (legumes)
• conspicuous winged margins
• turn from purple to russet-brown as they ripen
• bean-like seeds number 2+
• persist on tree after the leaves have fallen

Other notes:

• small tree to 30 feet
• first described by Linnaeus in 1753
• C. canadenis is native to eastern North America
• C. siliquastrum is native to China
• C. canadensis ‘Forest Pansy’ has dark leaves
• C. orbiculata/occidentalis is native to California and the American southwest
  • orbiculata – circular (Latin), referring to leaves
  • occidentalis – west (Latin), as in western US
  • before Euro-American settlement of California, Native Americans conducted purposeful burning of hillsides in the fall of the year, after redbud has shed its leaves, to encourage the growth of young, straight red-barked shoots used extensively in basketry
  • contemporary Native American weavers rely on coppicing (cutting back to a stump) to promote production of young straight shoots with a beautiful red pigment

Ecology & Adaptations:

• information in this section applies to C. orbiculata (formerly C. occidentalis) (Western or California redbud):
  • tree or shrub, 7-20 ft
  • native to California, Arizona and Utah
  • found in oak woodland, chaparral, mixed conifer forest, riparian woodland, and closed cone forest
  • at elevations of up to 4,000 feet, in canyons and on steep slopes, in gravelly and rocky soils along streams where it is never flooded
  • in the bottom of ephemeral streambeds in little pockets, benches, or crannies of boulder outcroppings
  • found in coarse, nutrient-poor soils that are well-drained
  • vegetative reproduction – re-sprouts vigorously after fires
  • pollination:
    • by bumble bees and orchard mason bees
    • flowers appear before leaves
  • seed germination & fire/drought/cold tolerance:
    • germination is favored by fire, which cracks the seed coat and generates the heat needed to stimulate germination
    • adapted to prolonged periods of dryness and cold and require special pretreatment to germinate, owing to an impervious seed coat plus a dormant embryo
  • seed dispersal by wind, birds, and animals
  • fire adapted – see vegetative reproduction and seed germination
  • adapted to low-nutrient conditions by hosting N-fixing bacteria in root nodules
  • drought tolerance – reduces net photosynthesis and stomatal conductance when water is limited, which reduces water demand and water loss
  • flood tolerance:
    • able to survive flooding for periods between 1 to 3 months during the growing season
    • root systems may produce few new roots or will be dormant during the flooded period