Coastal Larkspur Delphinium decorum
Coastal Larkspur is a perennial wildflower native to the lower 48 states. It blooms Mar – Jul.
More about this plant
Delphinium decorum is a species of larkspur known by the common names coastal larkspur and yellow-tinge larkspur. This wildflower is native to California and Oregon, where it grows on the slopes of the coastal ranges from the San Francisco Bay Area north to the southern Oregon coast. It has an erect stem which approaches half a meter in height at maximum. The leaves, which are divided into a number of narrow lobes, are mostly located about the base of the plant. The spindly stem above bears two to twenty widely spaced flowers. Each flower is carried on a pedicel several centimeters long. The five long, flat sepals are extended to give the face of the flower a star shape, and they are usually deep blue to purple. The petals are similar in color, except the top two may be lighter to almost white. The spur is very thin and may be nearly two centimeters long. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 11 derived from its U.S. range
- Lifespan
- Perennial
- Flower colour
- Purple AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~10 caterpillar species
Delphinium supports ~10 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 Delphinium in North America, including:
+ 8 more species → ↑ show fewer
Wildlife & visitors 2 nectaring
Open records of who else uses Coastal Larkspur — a generalist food-web signal, kept separate from the keystone Ecological Value.
2 adult butterfly & moth species are recorded nectaring at its flowers:
Related plants
More Delphinium →
How we know this (2) Methods & honest limits
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 (17) 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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