American Water Plantain Alisma subcordatum
American Water Plantain is a perennial wildflower native to Canada and the lower 48 states. It grows to 0.5 ft and blooms May in part shade – shade, with brown fruit.
More about this plant
Alisma subcordatum, the American water plantain, is a perennial aquatic plant in the water-plantain family (Alismataceae). This plant grows to about 3 feet in height with lance to oval shaped leaves rising from bulbous corms with fibrous roots. Any leaves that form underwater are weak and quick to rot; they rarely remain on adult plants. A branched inflorescence with white to pink 3-petaled flowers blooms from June to September. The seeds are eaten by waterfowl and upland birds. Native Americans dried and ate the submerged rootlike structures. The species name subcordatum means "almost heart-shaped". Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Part shade – shade
- Soil & moisture
- High moisture
- Soil pH
- 5–7
- Fertility need
- Medium
- Adapts to
- Medium (loam), Fine (clay)
- Hardiness
- USDA zone 4+
- Height
- 0.5 ft
- Spacing
- 3–5 ft apart from USDA planting density
- Spread
- None — clumping
- Growth rate
- Moderate
- Growth form
- Single crown
- Lifespan
- Perennial · moderate
- Foliage
- Broadleaf · medium texture
- Active growth
- Spring & summer
- Fruit
- Brown
- Propagate by
- Seed, Bare root, Sprigs
- Seed starting
- Needs cold stratification a cold-moist spell before it germinates
- Seeds ripen
- Summer seed-collection / harvest window
- In the trade
- Routinely available
- Resprouts if cut
- No
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Alisma in North America, including:
Wildlife & visitors 1 nectaring
Open records of who else uses American Water Plantain — a generalist food-web signal, kept separate from the keystone Ecological Value.
1 adult butterfly & moth species is recorded nectaring at its flowers:
Related plants
More Alisma →
How we know this (2) Methods & honest limits
We read each species’ measured specific leaf area (leaf area per unit dry weight) from the Global Spectrum dataset and band it: thin & fast (high SLA), medium, or thick & tough (low SLA). The global median is about 10 mm²/mg.
Honest limits: A species-mean from pooled measurements — individual plants vary with light and site. A broad strategy signal, not a precise per-plant figure.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
Sources for this entry (32) Open & cited
Cite this page Open data, please attribute
PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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