Swamp Loosestrife Decodon verticillatus
Swamp Loosestrife is a perennial shrub native to Canada and the lower 48 states. It grows to 8 ft and blooms Jul in full sun – part shade, with brown fruit.
More about this plant
Decodon verticillatus, the sole living species in the genus Decodon, is a flowering plant in the family Lythraceae. It is commonly known as waterwillow or swamp loosestrife. It is native to wetlands in the eastern half of the United States and Canada. Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Full sun – part shade
- Soil & moisture
- High moisture
- Soil pH
- 4.9–8.6
- Fertility need
- Medium
- Adapts to
- Coarse (sandy), Medium (loam), Fine (clay)
- Hardiness
- USDA zone 5+
- Height
- 8 ft
- Spacing
- 5–6 ft apart from USDA planting density
- Spread
- Rapid
- Growth rate
- Rapid
- Lifespan
- Perennial · long-lived
- Foliage
- Deciduous broadleaf · coarse texture
- Active growth
- Summer & autumn
- Fruit
- Brown
- Flower colour
- Pink AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed, Cuttings, Bare root, Container
- Seed starting
- No stratification needed
- Seeds ripen
- Summer – Autumn seed-collection / harvest window
- In the trade
- Routinely available
- Resprouts if cut
- Yes regrows after top-kill
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~5 caterpillar species
Decodon supports ~5 caterpillar species.
Native butterfly & moth caterpillars are the base of the terrestrial food web — most songbirds rear their young almost entirely on them. As a host for native Lepidoptera this is a modest genus.
Recorded feeding on Decodon in North America, including:
✦ Bees 11 bee visitors
11 native & managed bee species are documented visiting Swamp Loosestrife :
Wildlife & visitors 2 birds · 15 nectaring
Open records of who else uses Swamp Loosestrife — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 2 birds species (fruit, seed, browse):
15 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
Related plants
More Decodon →
How we know this (3) Methods & honest limits
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
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.
McKenzie et al. assigned each species a flower colour with a GPT-4V vision model over iNaturalist photos. We use the confident tier plus a separately-labelled lower-confidence top-up (mostly inconspicuous green/brown flowers), and render it as a small tint — never as an asserted fact, and kept out of the written synopsis.
Honest limits: AI image inference (~87% expert agreement on the confident tier); a decorative, confidence-tiered indicator, not a measured trait.
Sources for this entry (36) 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).
Loading…
BibTeX
Loading…