2. Dicentra Bernh. (bleeding heart)

Plants perennial, the rootstock with small clusters of tuberlike bulblets. Stems absent (slender rhizomes sometimes present). Leaves all basal, long-petiolate, the petiole (5–)8–24 cm long. Leaf blades usually 4 times compound and lobed, 4.5–9.0 cm long, ovate to broadly triangular in outline, the ultimate segments linear to narrowly oblong-elliptic or narrowly oblanceolate, rounded (but often with a minute, sharply pointed projection) to sharply pointed at the tip, green or the undersurface glaucous. Inflorescences 10–35 cm long, long-stalked and loosely to densely 3–15-flowered. Flowers bilaterally symmetrical in 2 perpendicular longitudinal planes, the stalks 2–14 mm long, pendant at flowering and fruiting, with a pair of small bractlets positioned noticeably below the flower. Sepals 2–5 mm long, triangular to broadly ovate, attached basally, rounded to more or less truncate base, the margins entire, membranous and white. Corollas white, sometimes pinkish-tinged, with a yellow to orangish yellow tip. Inner petals linear or nearly so toward the base, expanded above the midpoint with a broadly winged margin and a well-developed, entire to slightly undulate crest, rounded at the concave tip. Outer petals similar, variously shaped, short- to long-spurred, with a differentiated, ascending to spreading, concave tip, the body more or less rounded, not keeled or crested. Style persistent, relatively slender, the stigma 4-lobed, the lobes appearing as horns and/or wings. Fruits capsules, dehiscent (sometimes tardily so), 5–15 mm long, narrowly more or less ellipsoid (tapered at each end), straight, the surface often slightly swollen over the seeds, otherwise smooth, 3- to numerous-seeded. Seeds 1.5–2.5 mm long, somewhat flattened, more or less kidney-shaped in outline, rounded along the rim, the surface smooth or nearly so, black, shiny, the elaiosome an irregular, somewhat conic, white mass attached in the notch. About 19 species, temperate portions of North America, Asia.

The genus Dicentra is morphologically diverse, including both annuals and perennials, some of which have tall leafy stems and more or less paniculate inflorescences, and others that have climbing stems or solitary flowers (Stern, 1961). The generic description above applies only to the species found in the state. The tuberlike underground bulblets of the two Missouri species of Dicentra are derived from swollen petiole bases rather than from thickened roots or stems. Stern (1961) discussed the variety of swollen storage structures produced in the genus and his terminology is followed in the present work.

Although the morphology of the flowers, with the stamens massed around the stigma and enclosed in the corolla tip, suggests that inbreeding should be the main reproductive strategy, species of Dicentra are outcrossers. Pollination is mostly accomplished by long-tongued bees, principally queen bumblebees foraging for nectar after they emerge from hibernation and begin searching for a nesting site (Macior, 1970a, 1978a, b). These open the flower tips in search of nectar present in the spur and brush past the stigma, picking up and depositing pollen. Honeybees also are effective pollinators. Interestingly, some bumblebees rob the flowers of nectar by chewing through the spur instead of opening the flower from the tip.

Stern (1997b) noted that an extract from the bulbs of D. canadensis and D. cucullaria has been used to treat chronic skin diseases and syphilis, as well as a tonic and diuretic. One of the alkaloids in D. canadensis, bulbocapnine, has been used in the treatment of Ménière’s disease and muscle tremors, and as a pre-anesthetic. Some other species were used by Native Americans in the northwestern United States for worms. The species otherwise generally are considered highly poisonous.

Several species of Dicentra are cultivated as garden ornamentals, including the western North American D. eximia (Ker Gawl.) Torr. and D. formosa (Haw.) Walp., as well as the Asian D. spectabilis (L.) Lem. (all known as bleeding hearts for their pink, heart-shaped flowers). Steyermark (1963) excluded the last of these from the Missouri flora, stating that the sole historical collection from Linn County (C.A. Benson s.n. on 4 June 1930, in the University of Missouri herbarium) probably originated from a cultivated plant. A more recently collected specimen of D. spectabilis from St. Francois County (J. Sheets 41 on 12 April 1987) in the herbarium of Southeast Missouri State University likely also represents cultivated material For D. formosa ssp. formosa, a single specimen in the Missouri Botanical Garden Herbarium (W. H. Emig 330 on 23 April 1913) from the vicinity of Cliff Cave (Jefferson County) is part of a mixed collection that originally was mounted on the same sheet with D. cucullaria. In his monograph of the genus, Stern (1961) did not mention this specimen, but his annotation on the sheet indicates that he believed it to represent either a cultivated plant or more probably mislabeled material accidentally mounted on the wrong sheet. Because D. formosa occurs natively only from British Columbia to California and does not appear to escape from cultivation farther east, it is excluded from the Missouri flora in the present work.