nervosa – sinewy (Latin), referring to conspicuous veins in leaflets

Native range: W. North America

Leaves:

• alternate
• pinnately compound
• no spines on branches
• leaves spiney-dentate (or coarsely serrate-spiny)
• 9-19 leaflets (or 4-9 pairs)
• margin not undulate (compare M. aquifolium)
• veins not pinnate
• thick
• grey-green color
• dull on upper surface
• each leaflet with three central veins (vs. 1 in M. aquifolium)
• palmately 3-8 nerved

Flowers:

• inflorescence in clusters on short stalks (racemes)
• 4-8” long
• axillary
• yellow
• 3-parted

Fruit:

• berry
• dark purple

Other characteristics:

• shrub to 2 ft.
• rhizomatous
• bark is bright yellow inside (due to the alkaloid berberine)
• shredded bark of stems and roots was used by First Nations weavers to make a bright yellow dye for basket materials

Relevent info:

• often found in shade
• genus name has gone back and forth between Mahonia and Berberis for years, so be aware of both and use either

Ecology & Adaptations:

• native to both sides of the Cascades in Washington, southern British Columbia to California, also in northern Idaho
• habitat:
  • dry to fairly moist
  • open to closed forests
  • sea level to moderate elevations in the mountains
• tolerant of low nutrient substrates, such as coarse, shallow rocky soils, coarse alluvium, or glacial outwash
• evergreen leaves maximize function of investment in photosynthesizing structures
• shade tolerant
• drought tolerant:
  • thick leaves retain moisture
  • short vasicentric tracheids occur next to vessels throughout a growth ring, not in a longitudinal row, and can provide a subsidiary conducting system and maintain water columns (and conduction) to leaves when other tissues fail during drought
• vegetative reproduction:
  • Spreads through rhizomes
  • after fire or other disturbance, re-sprouts vigorously from rhizomes or rootstocks
• pollination by insects, including moths
• seed dispersal by animals that consume fruit
• herbivory protection – spines on leaf margins
• wildlife:
  • leaves are eaten especially in winter by elk and voles
  • fruits are eaten by small birds and mammals and sometimes black-tailed deer
  • nectar is favored by Anna’s hummingbird