Flower:

Racemes of up to 16 pale to bright golden yellow flowers that are initially erect, becoming horizontal to drooping with age. Flowers are tubular, 3/8 to ½ inch long with 2 pairs of petals and a straight to slightly curved spur at the back that is less than half as long as the rest of the flower. The outer upper petal is folded along a front midline and forms the spur. Both outer and inner petals broaden out to form ruffled lips at the opening; the upper curls up into a crest and the lower rolling out and down like a ruffled tongue. Outer petals have a spot of green in the center of the tip end that may turn yellow with age. Bracts are about ¼ inch long, narrowly lance-elliptic with a pointed tip. The uppermost leaves on a flowering branch typically do not rise above the raceme. Secondary clusters on lower branches have fewer flowers than upper branches and leaves usually rise above these clusters.

Often, plants produce small clusters of inconspicuous cleistogamous (petal-less, self-pollinating) flowers, characterized by a tight group of bracts at the tip of a branch. A plant may have only petaled flowers, only cleistogamous flowers, or both.

Leaves and stems:

Leaves are to 3 inches long, mostly twice pinnately compound, leaflets deeply divided with lobes further divided into narrow segments, giving them a feathery appearance. Lobes are typically widest above the middle, tips are mostly rounded with an abrupt, minute point. Surfaces are hairless, covered by a waxy bloom that often gives a blue-green or gray-green cast. Stems are multiple from the base, hairless, weakly angled, erect to prostrate with branches erect to ascending, and light green to reddish.

Fruit:

Fruit is an erect, pod-like capsule 3/8 to ½ inch long, usually stout, straight to slightly curved. Inside are tiny, shiny black seeds. Fruit from petaled flowers are single in the bract axils; fruit from cleistogamous flowers are tightly clustered at the branch tip.

Notes:

The pod-like fruits resemble those of members of the pea family, but this species is a relative of Dutchman's Breeches. Slender Fumewort is similar to another native yellow corydalis, Golden Corydalis (Corydalis aurea), which has leaves that typically over-top the primary flower clusters, has slightly larger flowers (½ inch or more), its capsules are mostly hanging and curved, seeds are larger, and plants do not have cleistogamous flowers. While their ranges overlap some, Slender Fumewort is uncommon and scattered in the southern third of the state, where Golden Corydalis is more common and present in most counties except in the southwest and south central part of the state. There are 3 subspecies of C. micrantha: subsp. micrantha is found in Minnesota and is described above, subsp. australis and texensis are southern species not found in Minnesota and have capsules usually ½ inch or larger.