Leonurus cardiaca L.


Leonurus cardiaca plant

Family - Lamiaceae

Stems - To +1.2m tall, herbaceous, multiple, rhizomatous, simple to branching above, minutely retrorse pubescent on angles, strongly 4-angled, hollow.

Leonurus cardiaca stemStem.

Leaves - Opposite, petiolate, 3-lobed, hirsute below (mostly on veins), pubescent above, reduced upward. Lowest leaves to +15cm broad, +12cm long. Lobes again divided or coarsely toothed. Petioles to +13cm long, 4-angled, densely pubescent and hirsute on upper margins (angles).

Leonurus cardiaca leavesLeaves.

Inflorescence - Axillary clusters of 11-12 sessile flowers almost completely surrounding stem and appearing as verticillasters (whorls).

Leonurus cardiaca inflorescenceInflorescence.

Flowers - Corolla bilabiate, tubular, constricted near base, densely pubescent to lanate externally, lanate near apex of throat internally, pinkish. Tube to 6mm long, 2.2mm in diameter. Lower lip reduced, 3-lobed. Lateral lobes small (-1mm long), recurved and folding under central lobe. Central lobe to 2mm long, attenuate, deflexed or slightly recurving, mottled with maroon near apex of throat. Upper lip 5-6mm long, +/-3mm broad, densely lanate above, obtuse, pink. Stamens 4, didynamous, slightly exserted beyond upper lip. Filaments white, to 1.6mm long, lanate (at least at base). Style 1, glabrous, positioned between upper pair of stamens. Stigma 2-lobed. Nutlets 4, densely hirsute at apex. Calyx bilabiate, with 5 ridges (nerves). Tube to 4mm long, glabrous. Upper lip with 3 lobes. Lobes attenuate, to 2mm long, spinose, with few hairs near apex. Lower lip 2-lobed. Lobes attenuate, 2.1mm long, deflexed or slightly recurved, spinose, with few hairs near apex.

Leonurus cardiaca flowersFlowers close-up.

Leonurus cardiaca flowersFlower side view.

Flowering - May - August.

Habitat - Pastures, waste ground, disturbed sites, roadsides, railroads.

Origin - Native to Eurasia.

Other info. - ...So I'm driving home and I spot a good planting of Delphinium ajacis. I decided to stop and take some snaps. Upon returning to my car I reached for my keys only to discover them still in my ignition and behind locked doors. The passenger window was cracked open a bit so I decided to look for some wire and fish my keys out. As I walked around an abandoned building I found not only some good wire, but also the plant pictured above. The moral of the story? - Always have a spare set of keys handy and ALWAYS have your camera.

Photographs taken off Mill Rd., Platte County, MO., 5-3-00, and in Marquette, MI., 7-27-02 (DETenaglia); also in Gallatin Conservation Area, Daviess County, MO, 6-13-2014 (SRTurner).