Hill Farm Nursery

Corydalis aurea – McLeese Lake, B.C. – May 17, 2014.  Image: HFN

Annual/Biennial. Zone 2. Fumariaceae. North America. Widespread throughout North America, in particular in areas disturbed by development, logging and forest fires. Common in the Cariboo-Chilcotin on recently disturbed ground – on graded roadsides, in gravel pits, and in newly logged areas.

This interesting and largely ephemeral early spring bloomer is occasionally abundant and always something of a surprise to see, appearing in the most unexpected places. Once it blooms in earliest spring, it quickly fades away after casting out its seeds, which can remain dormant for decades until germination conditions are again to its liking.

Technically a winter annual, Yellow Corydalis sprouts in the summer, makes an inconspicuous foliage clump which overwinters in semi-evergreen state, and then advances quickly into flowering stage in early spring. By July its life cycle is nearing its end; the beautiful, lacy, grey-green foliage is turning yellow and the plant is fading fast. No sign of it will be left by autumn.

Corydalis aurea – growing in a gravel pit near McLeese Lake, B.C. – May 17, 2014. Image: HFN

Plants expand quickly from their over-wintered rosettes, reaching 6 to 12 inches in height and spread. Roots are tap-rooted and fleshy, with spreading side roots. Foliage is rather “carrot-like” in appearance, being much divided, slightly succulent, and softly blue-green.

Tubular blooms are bright yellow blushed with green and are produced in great abundance during the few weeks of flowering time. Early-foraging wild bees are attracted to the nectar-rich blooms, and sometimes bore into the tubes to avoid having to negotiate their way past the stamens at the opening of the flowers.

Corydalis aurea – detail of flower cluster. Image: HFN

Seeds produced by Corydalis aurea are small, black and shiny, and form encased in slender, cylindrical pods. They are very attractive to ants, who aid in their dispersal by caching the seeds in underground storage chambers; it is theorized that when these nests are disrupted the seeds are brought back to the surface where they then germinate in great abundance.

This plant may be introduced into the rock garden as it is very showy in early spring, but as its ongoing garden presence depends upon random germination of the seeds and the plants themselves disappear after blooming, it should be sited with this in mind, and not depended on as a feature plant.

The tiny, slender, legume-like seed pods may be seen at the base of the central floral cluster. Image: HFN

Corydalis aurea is reportedly very toxic to sheep, and less so to cattle and horses, though I am unaware of any poisoning incidents in our region. Because of the plant’s early emergence, and its palatability – sheep paradoxically find it quite delicious – stock owners might be advised to keep an eye out for this plant when investigating their spring pastures before turnout.