Howell’s mariposa lily – State Wildlife Action Plan

Howell’s mariposa lily

Photo Credit: Oregon Department of Agriculture

Howell’s mariposa lily is a bulbous perennial, 2-4 dm tall, that bears a single large basal leaf (averaging 30 cm in length). These deep green, somewhat leathery basal leaves are distinctly parallel-veined with rows of hairs on the undersides that correspond to the veins. The broadly cup-shaped, showy flowers have three white to cream-colored petals 2.7-3 cm long, each with a lime green petal spot that is covered with dark purple hairs. The upper portions of the petals have few or no hairs. Each stem usually produces one or two (sometimes three) flowers, which develop into 2-cm-long capsules that remain erect until seeds are released. Plants begin to bloom in mid June and can continue into August under ideal conditions. In most populations, many more vegetative than reproductive plants occur, with only a relatively few mature individuals flowering each year. The number of plants flowering varies greatly among years and is dependent on seasonal conditions.

Overview

  • Species Common Name Howell's mariposa lily
  • Species Scientific Name Calochortus howellii
  • State Listing Status Threatened

Ecoregions

Special needs

Howell’s mariposa lily occurs on serpentine outcrops at lower to middle elevations. This species may be more common on brush-covered slopes or in scattered woods.

Limiting factors

Mining, off-road vehicle use, horticultural collecting, and grazing are among threats to this species.

Conservation actions

Manage grazing in occupied areas. Minimize impacts from mining. Monitor known populations.