Driving along Rogue River Siskiyou National Forest Road 4201 west of Oregon Highway 199 in Josephine County last June I noticed a hillside with white flowers I could not identify. Leonard is very good at stopping and backing up (obviously the road in not used much), so I was able to check out the plants. I could tell they were a mariposa lily, but had never seen one exactly like it before. My camera got a good workout.
Once home and able to check references I was glad we stopped. Howell’s mariposa lily (also called Howell’s mariposa tulip) is a rare, native perennial endemic to only Curry and Josephine Counties in Oregon between 1,300 and 3,000 feet. Howell’s mariposa lilies (Calochortus howellii) grow in hot, rocky places with serpentine soils. Serpentine soils are thin, have concentrations of heavy metals (magnesium, nickle, iron and chromium) and are low in calcium and nitrogen. As a result only hardy plants adapted to these extreme conditions survive here. Many rare species are endemic to the serpentine Siskiyou Mountains, Howell’s mariposa lily being one of them.
A member of the Lily Family (Lilaceae), Howell’s mariposa lily has an erect stem that arises from a bulb. There is a single deep green, somewhat leathery leaf with parallel veins arising at the base of the stem. Smooth on the upper surface, the leaf has rows of hairs on the underside that correspond to the veins. There is a pair of linear, bract-like leaves at the base of the flower stalk.
The flowers, one or several at the top of each stem, have three large, rounded, white or creme petals. The upper side of the petals have white hairs scattered over the upper surface and are hairless on the lower side. The hairs become very dense and purple brown above the greenish gland at the base of the petals. The three sepals are slightly shorter than the petals. A superior ovary and six stamens complete the flower.
The fruits are capsules that remain erect until the seeds are released.
This beautiful mariposa lily was named after Thomas Jefferson Howell (1842 – 1912). He collected over 500 specimens from Josephine County OR including 46 type specimens (pressed herbarium specimens upon which the plant description is based). Howell was one of Oregon’s earliest botanists and created the first species guidebook for the flora of the Pacific Northwest.