Foothill Larkspur Delphinium hesperium
Foothill Larkspur is a perennial wildflower native to the lower 48 states. It blooms Apr – Jul.
More about this plant
Delphinium hesperium is a species of larkspur known by the common name foothill larkspur. It is also sometimes called western larkspur and coastal larkspur, but these names are less specific since other species share them. It is endemic to California, where it grows in woodland and grassland in the northern half of the state. This wildflower generally reaches one-half to one meter in height. It has deeply lobed, prominently veined leaves, mostly located near the base of the plant. The inflorescence may hold very few to over 100 flowers, each on a long, thick pedicel. The flowers are usually a brilliant blue or purple, and sometimes lighter pinkish to white. Often, the sepals are dark in color, and the petals are lighter. The spur is about one to two centimeters (0.79 in) long. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 11 derived from its U.S. range
- Lifespan
- Perennial
- Foliage
- Broadleaf
- 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
✦ Bees 2 bee visitors
2 native & managed bee species are documented visiting Foothill Larkspur :
Wildlife & visitors 1 nectaring
Open records of who else uses Foothill Larkspur — a generalist food-web signal, kept separate from the keystone Ecological Value.
1 adult butterfly & moth species is recorded nectaring at its flowers:
Related plants
More Delphinium →
How we know this (3) Methods & honest limits
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.
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 (23) 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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