Perilla frutescens (L.) Britt.
Family - Lamiaceae
Stems - To 1m tall, erect, herbaceous, purple, 4-angled, from fibrous but tough roots, retrorse pubescent, with a single median vertical groove on each side of the stem. The entire plant fragrant.
Leaves - Opposite, petiolate, decussate. Petioles to +5cm long, antrorse pubescent, purple, with a very shallow adaxial groove. Blades ovate, serrate, acute, to +10cm long, +8cm broad, sometimes crisped or not, typically green above and purple-green or entirely purple below, mostly glabrous above, pubescent on the veins below, with any punctate glands below (use a lens to see). Lateral veins prominent and expressed below.
Inflorescence - Axillary and terminal indeterminate verticillasters to +15cm long. Axis retrorse pubescent (densely), the hairs purple. Flowers 2 at a node, decussate, each subtended by a single folded bract. Bracts broadly ovate when unfolded, entire, 3-5mm long and broad, glabrous but with ciliolate margins. Pedicels 1-2mm long in flower, longer in fruit, pubescent and glandular.
Flowers - Corolla pink, bilabiate, 4mm long, constricted near the base, pubescent externally, with a single band of long hairs at the base of the filaments internally. Upper lip 3-lobed. Central lobe deflexed, rounded, with a single shallow notch, 2-2.2mm broad, 1-1.5mm long. Lateral lobes rounded, 1.5mm broad, 1-1.2mm long, spreading. Lower lip single-lobed, lobe 2-2.3mm broad, 1-1.4mm long, reflexed. Lower lip bearded internally and with 2-4 darker pink spots internally. Stamens 4, adnate in the middle of the corolla tube, alternating with the corolla lobes, slightly exserted. Filaments white, pinkish at the apex, terete, glabrous, 2mm long. Anthers pinkish, fading to purple, bilobed, .5-.7mm broad. Style glabrous, 2-2.4mm long, included under the upper lip of the corolla, white, fading to lilac at the apex, terete. Ovary 4-parted, 1mm broad in flower, subtended by a nectariferous ring. The nectary with a basal appendage that protrudes slightly past the top of the ovary. Calyx bilabiate, the tube to 1.7mm long in flower, dark purple, hirsute externally, with a band of forward-facing hairs internally (at the base of the lobes). Upper lip 3-lobed. Lobes equal, 1.5mm long, 1mm broad, acute. Lower lip 2-lobed. Lobes attenuate, 2-2.2mm long, with antrorse strigose margins or not.
Flowering - August - October.
Habitat - Gravel bars, rich soils, alluvial soils or dry soils along streams, spring branches, gravel bars, roadsides, railroads.
Origin - Native to India.
Other info. - This weedy but showy species can be found mostly in the southern half of Missouri. It is very easy to identify, especially while in flower, as no other plant looks or smells quite like it. The purple stems and distinctive leaves are good characters for identification. The leaves of some plants can be crisped, other may not be. Both types of plants can grow right next to each other and are, at most, phases of the species.
Seedling plant with typical leaves.
Top of crisped plant.
Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 9-20-03.