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Home / Browse / Arabis / Creamflower Rockcress (var. pycnocarpa)
iNaturalist — CC, credited & licensed per image
Pictured: Arabis hirsuta — the species. This variety isn’t separately illustrated.
Brassicaceae family

Creamflower Rockcress (var. pycnocarpa) Arabis hirsuta var. pycnocarpa variety

Native Specialist-bee host

Creamflower Rockcress (var. pycnocarpa) is an annual wildflower native to Alaska, Canada, and the lower 48 states. A host for pollen-specialist native bees.

More about this plant

Arabis hirsuta, known as hairy rock-cress, is a flowering plant in the family Brassicaceae. In previous North American works, this species has been broadly defined to include plants native to Europe, Asia, and the northern half of North America, but is now more often restricted to a narrower subgroup restricted to Europe. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 4 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
Lifespan
Annual
In the garden
Herb layer — Sits in the herb of a layered food forest or polyculture.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 ~7 caterpillar species

Arabis supports ~7 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 Arabis in North America, including:

Anthocharis sara · Sara Orangetip Colias occidentalis · Western Sulphur Euchloe ausonides · Large Marble Euchloe creusa · Northern Marblewing Euchloe hyantis · California Marble Euchloe olympia · Olympia Marble
+ 8 more species →
Hellula rogatalis · Cabbage Webworm Moth Paramidea lanceolata · white / sulphur butterfly Paramidea midea · white / sulphur butterfly Pieris napi · Green-Veined White Pieris virginiensis · West Virginia White Pontia beckerii · Becker's White Pontia occidentalis · Western White Pontia protodice · Checkered White
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).
✦ Bees specialist-bee host

Specialist native bees depend on it.

Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Arabis is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.

Xerces pollinator conservation →
Specialist hosts from Smith et al. 2024.
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.
Sources for this entry (12) 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 — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[06] Description — Wikipedia (CC BY-SA)
[07] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts · Smith et al. 2024 (CC BY)
[08] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[10] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[11] Caterpillar species — NHM HOSTS (CC0)
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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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