Persicaria maculosa Gray

Lady's Thumb

© SRTurner

Family - Polygonaceae

Habit - Annual, taprooted forb, the stems also occasionally rooting at the lower nodes.

	Roots.
© SRTurner

Stems - Spreading to erect, to 70 cm, glabrous or appressed-hairy, not glandular, typically reddish at nodes. Ocreae persistent, usually tearing with age, 4-30 mm long, somewhat inflated toward the base, tan to light brown and papery throughout, truncate, not oblique at the tip, lacking a flange of tissue at the tip, the margin with bristles 1.0-3.5 mm long, the surface glabrous or appressed-hairy, not gland-dotted.

	Old stem and nodes.
© SRTurner

	Young stem and leaves.
© SRTurner

	Ocrea.
© SRTurner

Leaves - Alternate, simple. Petioles absent or to 0.8 cm long. Leaf blades 5-10 cm long, 1.0-2.5 cm wide, linear-lanceolate to lanceolate or narrowly ovate, angled or tapered at the base, angled or tapered to a sharply pointed tip, the surfaces glabrous or sparsely appressed-hairy especially along the main veins, unarmed, the undersurface sometimes with impressed glands, the upper surface often with a reddish or purplish, chevron-to crescent-shaped or triangular area.

	Leaf adaxial, with a central darker splotch.
© SRTurner

	Leaf adaxial. This leaf lacks a darker splotch.
© SRTurner

	Leaf adaxial surface.
© SRTurner

	Leaf abaxial.
© SRTurner

	Leaf abaxial surface.
© SRTurner

	Pressed leaves.
© DETenaglia

Inflorescences - Terminal and axillary from the upper leaves (sometimes also with small clusters of flowers at the median and lower nodes), solitary or more commonly several to numerous per main stem, 1.0-4.5 cm long, 7-12 mm wide, erect or ascending, straight, dense, uninterrupted, the stalk 1-5 cm long, glabrous (occasionally appressed-hairy elsewhere), not glandular. Ocreolae mostly overlapping, the margins glabrous or more commonly with bristles 0.2-1.0 mm long, the surface glabrous, not gland-dotted.

	Inflorescences.
© SRTurner

Flowers - Perfect, 4-14 per fascicle, all similar. Perianth white to greenish white toward the base, pinkish-tinged to pink toward the tip, bell-shaped, not gland-dotted, the tepals 4 or 5, 2.0-3.5 mm long, fused below the midpoint, the nerves irregularly few-branched, forming a network toward the base (not anchor-shaped). Stamens 4-8, not exserted, the anthers yellow or pink. Styles 2-or 3-branched from near the base, not exserted, not persistent.

	Open flowers.
© SRTurner

Fruits - Achenes 2-3 mm long, 1.5-2.5 mm wide, not or only slightly exserted, discoid or 3-angled, beakless, the faces flat or slightly concave, lacking a central hump, the surface smooth, dark brown to black, shiny.

	Maturing achenes breaking through tepals.
© SRTurner

Flowering - May - October.

Habitat - Streambanks, spring branches, sloughs, fens, bottomland forests, openings of mesic upland forests, moist swales in sand prairies, fields, gardens, ditches, railroads, roadsides, and open disturbed areas; occasionally emergent aquatics.

Moist to wet waste ground, disturbed sites, meadows, streambanks, roadsides, railroads.

Origin - Native to Eurasia.

Lookalikes - Several other pink-flowered species of Persicaria.

Other info. - This species is found in wet areas across most of Missouri, and across most of the continental U.S. It can sometimes be recognized by the characteristic purple splotch in the center of the leaf; however, this is not always present. The inflorescence stalks are neither hairy nor glandular. Characters to look for are stem node ocreae with bristles at the top (though these are usually short) and pinkish inflorescences typically about 1 cm in diameter. There are normally several of these on each plant. Older specimens often have bare, reddish lower stems with conspicuous swellings.

The plant is common in the habitats mentioned above and is somewhat toxic. This species somewhat resembles P. longiseta but the latter has a more rose-colored perianth and the bracts of the inflorescence have cilia which typically are longer than the flowers.

Photographs taken at the Kansas City Zoo, 5-30-99 and 5-11-00 (DETenaglia); also at Creve Coeur Lake Park, St. Louis County, MO, 8-6-2020, near Labadie, Franklin County, MO, 8-6-2020, and at East Central College, Franklin County, MO, 9-14-2023 (SRTurner).