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Lesser Marsh St. Johnswort

Triadenum tubulosum

Last reviewed: August 2026

Lesser Marsh St. Johnswort (Triadenum tubulosum)
Photo: (c) Laura Clark, some rights reserved (CC BY), uploaded by Laura Clark

Toxicity unknown

Lesser Marsh St. Johnswort (Triadenum tubulosum) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

part sun

Water

high

Size

6"–24" H × 4"–12" W

Bloom

Jun, Jul, Aug, Sep

Native to

AL, AR, FL, GA and 15 more states

Pollinators

bees, beetles

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 459 programs across 44 states, each with a link to the provider and the date we last checked it.

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Browse plants for this ecoregion

South Central PlainsOzark HighlandsPiedmontSoutheastern PlainsInterior PlateauInterior River Valleys and HillsMississippi Alluvial PlainMississippi Valley Loess Plains

Lesser marsh St. Johnswort is a compact native perennial that thrives in consistently moist soils and partial sun conditions. It produces small yellow flowers from summer through early fall and maintains a low, bushy growth habit. This wetland plant is ideal for rain gardens, pond edges, or areas with poor drainage.

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In an HOA neighborhood

Lesser Marsh St. Johnswort takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.

Works well in: backyard only.

  • Requires consistently wet conditions that may look messy
  • Unknown winter appearance could be problematic
  • Small stature may appear unkempt in formal landscapes

Wildlife value

The flowers attract native bees and beetles during the long blooming season from June through September. Its presence in wet areas also supports beneficial insects that contribute to overall garden ecosystem health.

Common questions

How much sun does Lesser Marsh St. Johnswort need?
Lesser Marsh St. Johnswort grows best in part sun conditions.
When does Lesser Marsh St. Johnswort bloom?
Lesser Marsh St. Johnswort blooms in June, July, August, and September.
Where is Lesser Marsh St. Johnswort native?
Lesser Marsh St. Johnswort (Triadenum tubulosum) is native to AL, AR, FL, GA and 15 more states, per the World Checklist of Vascular Plants (Kew).
What pollinators does Lesser Marsh St. Johnswort attract?
Lesser Marsh St. Johnswort draws bees and beetles.
Is Lesser Marsh St. Johnswort HOA-friendly?
Lesser Marsh St. Johnswort takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

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