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Clusiaceae family

Grassy St. Johnswort Hypericum gramineum

Grassy St. Johnswort is an introduced annual herb, found in Hawaii. It grows to 0.7 ft.

More about this plant

Hypericum gramineum, commonly known as small St. John's wort or grassy St. Johnswort, is species of flowering plant in the St. Johns wort family Hypericaceae. It is found in parts of Southeast Asia, Oceania, and the Pacific. Wikipedia →

Growing & care

USDA PLANTS · TRY
Size & form
Sources · Size & form
TRY Plant Trait Database (CC BY 4.0) — Height · Foliage
USDA PLANTS — Lifespan
Height
0.7 ft
Lifespan
Annual
Foliage
Broadleaf
In the garden
Ground-cover layer — Sits in the ground-cover of a layered food forest or polyculture.Open guide →
Living mulch / groundcover — Low, ground-hugging grower — can carpet bare soil as a living mulch, shading out weeds and holding moisture.Open guide →
derived roles
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
Leaf build Direct fact

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.

Díaz, S. et al. (2022) The global spectrum of plant form and function: enhanced species-level trait dataset. Scientific Data 9:755.
Photosynthesis Direct fact

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.

Kattge, J. et al. TRY plant trait database — Categorical Traits Dataset (2012).
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 (15) 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)
[05] Invasive / introduced status — US-RIIS v2.0 (USGS)
[07] Description — Wikipedia (CC BY-SA)
[08] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[11] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[12] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[14] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[15] Caterpillar species — NHM HOSTS (CC0)
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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