Valley Redstem Ammannia coccinea
Valley Redstem is an annual shrub native to the lower 48 states, Puerto Rico, and the U.S. Virgin Islands. It grows to 1.6 ft and blooms Jun – Nov in part shade – shade.
More about this plant
Ammannia coccinea is a species of flowering plant in the loosestrife family known by several common names, including valley redstem, scarlet toothcup, and purple ammannia. It is native to most of the contiguous United States, with the exception of the Pacific Northwest and New England. It is generally found in moist areas, such as riverbanks and pond margins. It is weedy in some areas. This is an annual herb growing erect to heights approaching one meter or lying along the ground. Leaves are linear in shape, up to 8 centimeters long, and green to shades of deep red in color. The inflorescence is a cluster of 3 to 5 flowers growing in the leaf axils along the upper part of the stem. The rounded flower has small rose to lavender petals each a few millimeters long and protruding stamens with yellow anthers. The fruit is a rounded capsule up to half a centimeter wide containing many tiny seeds. Wikipedia →
Growing & care
USDA PLANTS · TRY- Sun
- Part shade – shade
- Soil & moisture
- Medium moisture
- Soil pH
- 4–5.9
- Fertility need
- Medium
- Adapts to
- Medium (loam), Fine (clay)
- Hardiness
- USDA zone 4+
- Height
- 1.6 ft
- Spread
- None — clumping
- Growth rate
- Moderate
- Growth form
- Single crown
- Lifespan
- Annual
- Foliage
- Broadleaf · medium texture
- Active growth
- Spring
- Flower colour
- Pink AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed
- Seed starting
- No stratification needed
- Seeds ripen
- Spring – Autumn seed-collection / harvest window
- In the trade
- No known commercial source
- Resprouts if cut
- No
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →✦ Bees 9 bee visitors
9 native & managed bee species are documented visiting Valley Redstem :
+ 3 more bees → ↑ show fewer
Wildlife & visitors 2 birds · 2 nectaring
Open records of who else uses Valley Redstem — a generalist food-web signal, kept separate from the keystone Ecological Value.
Recorded eaten by 2 birds species (fruit, seed, browse):
2 adult butterfly & moth species are recorded nectaring at its flowers:
Related plants
More Ammannia →
How we know this (3) 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.
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 (31) 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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