American Bluehearts

American blue hearts blooming flower stalk
Scientific Name
Buchnera americana
Orobanchaceae (broomrapes); formerly Scrophulariaceae (figworts)

American bluehearts is an annual, single or few-stalked, unbranching wildflower of prairies and glades. It has distinctive, showy purple flowers that turn black as they age. The stem and leaves are hairy and rough to the touch and darken when injured or picked.

The leaves are opposite, stalkless, lance-shaped to broadly oval, to about 2½ inches long, with a few coarse teeth.

The flowers form a rather dense spike at the top of the stalk. Each flower has a tubular, 5-lobed calyx at the base that has two leaflike bracts enfolding its base. After the flowers are spent and the fruits mature, the calyx dries, swells, flares open, and looks like a little tan urn. The petals are purple and trumpet shaped with 5 flaring, unequal lobes. The tube is hairy inside and outside. Flowers turn black as they dry up. Blooms June–September.

American bluehearts is partially parasitic on other plants. Its roots form knobby, tuberous connections to the roots of host plants from which it steals nutrients. Although some members of its family cannot live without a host plant, American bluehearts has green chlorophyll in its leaves and is capable of living, at least for a time, without a host plant, especially when plenty of nutrients are available and conditions are not droughty or otherwise stressful. Those that connect to host plants almost always are more vigorous than those that don’t.

Similar species: At first glance, you might think it looks like a phlox, a loosestrife, Venus’ looking glass, or dame’s rocket. Paying attention to the characters above should remove any doubt, as American bluehearts is distinctive.

Other Common Names
Blue Hearts

Height: stems 1–3 feet.

Where To Find

Scattered south of the Missouri River, but absent from the Bootheel lowlands.

Occurs in upland prairies, glades, and savannas; also occasionally found in old fields and roadsides.

It is scattered widely in the eastern United States and in parts of Canada and Mexico. In some places, it is considered threatened or endangered, mostly due to destruction of appropriate habitats.

Native Missouri wildflower.

This showy and fascinating native wildflower is declining in some of its former North American range because of habitat loss. Uninterrupted native prairies once covered vast parts of our continent, and conversion of those habitats to agricultural crops is a main reason they have disappeared. Fire suppression, which allowed trees to take over prairies, is another. Native tallgrass prairie is staggeringly diverse botanically. One never-plowed prairie remnant in Dade County recently was found to have nearly 300 plant species on its 160 acres. Researchers found 46 native plant species within a single square-meter plot — a world record!

In the middle 1700s, Linneaus created the genus name, Buchnera, to honor his scientific correspondent Andreas Elias Büchner (1701–1769). Büchner was a physician and naturalist based in today’s German states of Saxony-Anhalt and Thuringia.

The common English name of this family deserves some explanation. The word “broomrape” comes from the English word “broom” (which few Americans use in its old-fashioned sense, to refer to various shrubs in the bean family), plus the Latin word rapum, which means “tuber,” as in turnips (Brassica rapa) and in rapeseed, which comes from a close relative of turnips. Put them together, and “broomrape” means something like “bean-shrub tuber” or “root swelling on bean shrubs.” It refers to the tuberous connections the parasite forms on the host plant’s roots.

Although members of the broomrape family may parasitize a number of different host plants, some famous Old World broomrapes parasitize members of the bean family. Since these are economically important crops, it’s easy to see why people would notice the knobby, tuberlike connections between the parasitic broomrapes and suffering crop plants.


American bluehearts can have a variety of host plants, including several species of pines and oaks, plus sugarberry (southern hackberry), green ash, sweet gum, tulip tree, water tupelo, black gum, sycamore, and eastern cottonwood. Prairies, by definition, have very few trees. But historically, Missouri’s prairies, glades, savannas, and open woodlands formed a patchwork of open, grassy habitats that were kept open by occasional fires.

This is Missouri’s only representative of the genus Buchnera. Globally, there are about 100 species in North and South America, the Caribbean Islands, Africa, and Asia south to Australia.

You might be familiar with some other Missouri members of the broomrape family (Orobanchaceae) (orr-oh-ban-KAY-see-ee): Indian paintbrushes (Castilleja spp.); gerardias and false foxgloves (Agalinis, Aureolaria, and Dasistoma species); beechdrops (Epifagus virginiana); broomrapes (Orobanche spp.); and louseworts or wood betonies (Pedicularis spp.).

The common buckeye butterfly uses bluehearts, as well as a number of other plants, many in the broomrape family, as caterpillar food plants.

Members of the broomrape family used to be considered part of the once-huge snapdragon family (Scrophulariaceae), but molecular (DNA) evidence convinced researchers that the snapdragon family should be broken up into several separate families.

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Similar Species
About Wildflowers, Grasses and Other Nonwoody Plants in Missouri
A very simple way of thinking about the green world is to divide the vascular plants into two groups: woody and nonwoody (or herbaceous). But this is an artificial division; many plant families include some species that are woody and some that are not. The diversity of nonwoody vascular plants is staggering! Think of all the ferns, grasses, sedges, lilies, peas, sunflowers, nightshades, milkweeds, mustards, mints, and mallows — weeds and wildflowers — and many more!