Persicaria maculosa
Lady's thumb, Lady's Thumb
(c) Joe Potter Butler, some rights reserved (CC BY), uploaded by Joe Potter Butler · licence
Family: Polygonaceae · Type: Herb · Not Native
Persicaria maculosa (Lady's thumb) is a non-native California herb in the Polygonaceae family, recognized by dark leaf blotches diagnostic when present.
Lady's thumb is a naturalized annual found in California in moist disturbed areas and fields at elevations below 1,500 meters. Flowering from June to November, this plant produces pink or rose flowers in small clusters 7 to 12 millimeters wide. Growing with prostrate to erect stems 10 to 70 centimeters tall, it often has a distinctive dark blotch on its lance-shaped leaves. Its leaves are 5 to 10 centimeters long with tapered bases and acute tips, featuring light-brown cylindric ocreae with short bristly margins. The fruit is a shiny, smooth, lens-shaped seed 2 to 2.7 millimeters long that turns brown-black when mature.
Identification and appearance
Key characters: 8 sympatric species; dark leaf blotches diagnostic when present
Habitat and range
Habitat: Moist disturbed areas, fields
Elevation: < 1500 m
California counties: San Diego, San Luis Obispo, Los Angeles, Ventura, Plumas, Modoc, San Mateo, Alameda, Alpine, Amador, Glenn, Inyo, Lake, Lassen, Madera, Merced, Monterey, Napa, Placer, San Bernardino, Santa Clara, Santa Barbara, Santa Cruz, Shasta, Sierra, Solano, Sutter, Tehama, Trinity, Yuba, Butte, Calaveras, Del Norte, El Dorado, Humboldt, Kern, Marin, Mariposa, Mendocino, Nevada, San Francisco, San Joaquin, Siskiyou, Sonoma, Tuolumne, Sacramento, Colusa, Contra Costa, Riverside, Imperial, Yolo, Tulare
Outside California: North America, native to Eurasia
Bloom period
Persicaria maculosa blooms Jun-Nov.
How to tell it apart
vs Polygonum: Persicaria has opaque stem sheaths; Polygonum has translucent sheaths that split into two lobes.; vs Rumex: Persicaria has spike-like pink/white flower clusters; Rumex has branched greenish flower clusters.; vs Trifolium: Persicaria has spike/head flower clusters and papery stem sheaths; Trifolium has clover heads and no sheaths.; vs Salix: Persicaria is an herb with flower spikes; Salix is a woody shrub with catkins.; vs Phytolacca: Persicaria has small pink/white flowers in spikes; Phytolacca has white-green flowers and dark purple berries.
Frequently asked questions
Is Persicaria maculosa native to California?
No. Persicaria maculosa is not native to California (recorded as not native).
When does Persicaria maculosa bloom?
Persicaria maculosa blooms Jun-Nov.
Where in California does Persicaria maculosa grow?
Persicaria maculosa occurs in San Diego, San Luis Obispo, Los Angeles, Ventura, Plumas, Modoc, San Mateo, Alameda and other counties, at elevations of < 1500 m.
What plant family does Persicaria maculosa belong to?
Persicaria maculosa is in the Polygonaceae family, genus Persicaria.
What habitat does Persicaria maculosa grow in?
Persicaria maculosa grows in Moist disturbed areas, fields.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.