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Clusiaceae family

Coppery St. Johnswort Hypericum denticulatum

Native

Coppery St. Johnswort is a perennial wildflower native to the lower 48 states. It grows to 2 ft and blooms Jun in full sun – part shade, with brown fruit.

More about this plant

Hypericum denticulatum, the coppery St. John's Wort, is a perennial herb in the flowering plant family Hypericaceae. It is native to the Eastern United States. The species has two varieties, H. denticulatum var. recognitum and H. denticulatum var. acutifolium. The herb has a diploid number of 24 or 48. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
USDA PLANTS — Sun · Soil & moisture
USDA — SoilPH — Soil pH
USDA PLANTS (DwCA, Zenodo 17903503) — Fertility Requirement / Soil Adaptation — Fertility need · Adapts to
USDA — Temp-Min °F — Hardiness
Sun
Full sun – part shade
Soil & moisture
Medium moisture
Soil pH
4.8–6.4
Fertility need
Low
Adapts to
Coarse (sandy), Medium (loam), Fine (clay)
Hardiness
USDA zone 8+
Size & form
Sources · Size & form
USDA PLANTS (DwCA, Zenodo 17903503) — Height, Mature — Height
USDA PLANTS (DwCA, Zenodo 17903503) — Planting Density (per acre) — Spacing
USDA PLANTS (DwCA, Zenodo 17903503) — Growth Rate / Spread / Growth Form / Lifespan / Active Growth Period / Seed Period — Spread · Growth rate · Growth form · Active growth
USDA PLANTS — Lifespan
TRY Plant Trait Database (CC BY 4.0) · USDA PLANTS — Foliage
USDA PLANTS (DwCA, Zenodo 17903503) — Fruit/Seed Color / Fruit Persistence — Fruit
McKenzie et al. 2025 — community-science image analysis (MIT) — Flower colour
Height
2 ft
Spacing
2.5–3 ft apart from USDA planting density
Spread
None — clumping
Growth rate
Slow
Growth form
Single crown
Lifespan
Perennial · moderate
Foliage
Broadleaf · coarse texture
Active growth
Summer
Fruit
Brown
Flower colour
Yellow AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
In the garden
Sources · In the garden
USDA PLANTS (DwCA, Zenodo 17903503) — Propagation Method / Commercial Availability — Propagate by · In the trade
USDA PLANTS (DwCA, Zenodo 17903503) — Germination (cold stratification) — Seed starting
USDA PLANTS — Seed Period — Seeds ripen
USDA PLANTS (DwCA, Zenodo 17903503) — Foliage Texture / Browse Palatability / Resprout — Resprouts if cut
Propagate by
Container, Sprigs
Seed starting
Needs cold stratification a cold-moist spell before it germinates
Seeds ripen
Summer seed-collection / harvest window
In the trade
No known commercial source
Resprouts if cut
No
Herb layer — Sits in the herb of a layered food forest or polyculture.Open guide →
Rain garden / bioswale — Rated FACW on the wetland list — tolerates wet feet, so it suits the soggy zone of a rain garden or bioswale that catches and filters runoff.Open guide →
derived roles
AI = read by an AI vision model · DERIVED = a computed estimate, not a direct measurement. The “How we know this” section below details each.
The garden year bloom → fruit → fall colour
J
F
M
A
M
J
J
A
S
O
N
D
Bloom
Bloom (the flower's colour)
Bloom · Jun — USDA PLANTS (DwCA, Zenodo 17903503) — BloomPeriod
When to sow · for your area

Sow timing keys off your local last- and first-frost dates.

Species characteristics from USDA PLANTS (public domain) + TRY (CC BY) — general guidance, not a guarantee for your exact site. Deer "browsing" is documented palatability, not a deer-proof claim.

Wildlife & pollinators

How pollinator value is scored →
❧ Caterpillar hosts ~20 caterpillar species

Hypericum supports ~20 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 moderate genus.

Recorded feeding on Hypericum in North America, including:

Acleris aenigmana · leafroller moth Acleris maculidorsana · Stained-Back Leafroller Agonopterix hyperella · concealer moth Agonopterix lythrella · concealer moth Agonopterix nubiferella · concealer moth Aplocera plagiata · Treble-Bar
+ 8 more species →
Caloptilia hypericella · leaf-blotch miner moth Choristoneura parallela · Spotted Fireworm Moth Choristoneura rosaceana · Oblique-Banded Leafroller Coleotechnites nigritus · twirler moth Cryptocala acadiensis · Catocaline Dart Fomoria hypericella · pygmy leafminer moth Hemithea aestivaria · Common Emerald Hyppa xylinoides · Common Hyppa
Keystone count (genus-level) from Warren II 2026 (CC0) · Tallamy host-use records. Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0).
Species thumbnails re-hosted from iNaturalist — Creative Commons, credited per image (hover for credit). Click any species to see it on iNaturalist. Not exhaustive; many taxa have no openly-licensed photo yet.
How we know this (2) Methods & honest limits
Climate niche (heat tolerance & native rainfall) Derived

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.

Realized-niche / climate-envelope approach (Pearson & Dawson 2003; Soberón 2007). Climate: NOAA NCEI nClimDiv county normals (1991–2020).
Flower colour Derived

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.

McKenzie, P., Berardi, A.E., Hopkins, R. (2025). flower_color_phenology (MIT).
Derived values are computed from open data by a published method — labelled, cited, and never shown as a direct observation. Full methodology →
Sources for this entry (28) Open & cited
[01] Scientific name & family — USDA PLANTS (DwCA, Zenodo 17903503)
[02] Growth habit & duration — USDA PLANTS (DwCA, Zenodo 17903503)
[03] Native status & distribution — USDA PLANTS (DwCA, Zenodo 17903503)
[04] Common name — USDA PLANTS (via GBIF)
[18] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[19] Wetland indicator — USACE National Wetland Plant List (2022)
[21] Description — Wikipedia (CC BY-SA)
[22] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[24] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[26] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[27] Caterpillar species — NHM HOSTS (CC0)
[28] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
Spot an error or have a better photo? Every field links to its source, and the whole dataset is open.
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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