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Asteraceae family

Carquinez Goldenbush Isocoma arguta

Native Specialist-bee host
Late-season nectar — Flowers in a late-autumn window when few other plants in our catalog bloom — valuable late forage for pollinators (relative to our catalog's bloom coverage).

Carquinez Goldenbush is a perennial shrub native to the lower 48 states. It blooms Sep – Oct. A host for pollen-specialist native bees.

More about this plant

Isocoma arguta is a rare species of flowering plant in the family Asteraceae known by the common name Carquinez goldenbush. It has been found only in Solano and Contra Costa Counties in California, where it grows in the Sacramento-San Joaquin River Delta. It is a resident of Suisun Marsh. It thrives on alkali flats and other mineral-rich soils. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
Cold hardiness (derived) — Hardiness
Hardiness
≥ zone 11 derived from its U.S. range
Size & form
Sources · Size & form
USDA PLANTS — Lifespan
Lifespan
Perennial
In the garden
Shrub layer — Sits in the shrub of a layered food forest or polyculture.Open guide →
derived roles
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 · Sep – Oct — 15 obs · Herbarium specimens — Park et al. 2023 (CC BY 4.0)
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 Documented caterpillar host
Named species (a documented Nearctic sample, not exhaustive) from NHM HOSTS (CC0).
✦ Bees specialist-bee host · 1 bee visitor

Specialist native bees depend on it.

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

Xerces pollinator conservation →

1 native & managed bee species is documented visiting Carquinez Goldenbush :

Apis mellifera · Honey Bee
Specialist hosts from Smith et al. 2024. Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI →
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 (16) 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] Wetland indicator — USACE National Wetland Plant List (2022)
[08] Description — Wikipedia (CC BY-SA)
[09] Ecological value — GloBI · Smith et al. 2024 (CC BY)
[11] Conservation rank — NatureServe Explorer (CC BY)
[12] Cold hardiness (derived) — Derived from U.S. range × USDA PHZM zones
[14] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[15] Caterpillar species — NHM HOSTS (CC0)
[16] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
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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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