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iNaturalist — CC, credited & licensed per image
Ranunculaceae family

Sierra Larkspur Delphinium glaucum

Native
Deer favourite — Rated highly palatable to browsing deer — so where deer are around, expect this one to get nibbled. It's a documented preference, not a certainty: pressure swings with the place and season, and a fenced or low-deer yard may be untouched.
USDA livestock toxicity rating — not a pet assessment. See the Toxicity detail further down for what's documented.

Sierra Larkspur is a perennial wildflower native to Alaska, Canada, and the lower 48 states. It grows to 8 ft and blooms Mar in full sun, with black fruit.

More about this plant

Delphinium glaucum, known by the common names Sierra larkspur, mountain larkspur, and glaucous larkspur, is a species of wildflower in the genus Delphinium, which belongs to the buttercup family, Ranunculaceae. It is native to western North America from Arizona to Alaska, growing in moist mountainous environments such as riverbanks and meadows. Wikipedia →

Growing & care

USDA PLANTS · TRY
Conditions
Sources · Conditions
USDA PLANTS — Sun · Soil & moisture
USDA — SoilPH — Soil pH
USDA PLANTS (DwCA, Zenodo 17903503) — Fertility Requirement / Soil Adaptation — Fertility need · Adapts to
USDA — Temp-Min °F — Hardiness
Sun
Full sun
Soil & moisture
High moisture
Soil pH
5.6–7
Fertility need
High
Adapts to
Coarse (sandy), Medium (loam), Fine (clay)
Hardiness
USDA zone 5+
Size & form
Sources · Size & form
USDA PLANTS (DwCA, Zenodo 17903503) — Height, Mature — Height
Derived (allometric) — width = height × functional-class crown ratio fit on USDA Urban Tree DB · Tallo; method per Jucker et al. 2022, Pretzsch et al. 2015 — Mature width
USDA PLANTS (DwCA, Zenodo 17903503) — Growth Rate / Spread / Growth Form / Lifespan / Active Growth Period / Seed Period — Spread · Growth rate · Growth form · Active growth
USDA PLANTS — Lifespan
TRY Plant Trait Database (CC BY 4.0) · USDA PLANTS — Foliage
USDA PLANTS (DwCA, Zenodo 17903503) — Fruit/Seed Color / Fruit Persistence — Fruit
McKenzie et al. 2025 — community-science image analysis (MIT) — Flower colour
Height
8 ft
Mature width
~ 7 ft wide DERIVED derived estimate — open-grown crown allometry (height × growth-form ratio); not a measurement
Spread
None — clumping
Growth rate
Rapid
Growth form
Multiple stems
Lifespan
Perennial · short-lived
Foliage
Broadleaf · medium texture
Active growth
Spring & summer
Fruit
Black
Flower colour
Purple AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
In the garden
Sources · In the garden
USDA PLANTS (DwCA, Zenodo 17903503) — Propagation Method / Commercial Availability — Propagate by · In the trade
USDA PLANTS (DwCA, Zenodo 17903503) — Germination (cold stratification) — Seed starting
USDA PLANTS — Seed Period — Seeds ripen
USDA PLANTS (DwCA, Zenodo 17903503) — Foliage Texture / Browse Palatability / Resprout — Deer browsing · Resprouts if cut
Propagate by
Seed
Seed starting
Needs cold stratification a cold-moist spell before it germinates
Seeds ripen
Summer – Autumn seed-collection / harvest window
In the trade
Routinely available
Deer browsing
High browsed readily
Resprouts if cut
No
Shrub layer — Sits in the shrub of a layered food forest or polyculture.Open guide →
Rain garden / bioswale — Rated FACW on the wetland list — tolerates wet feet, so it suits the soggy zone of a rain garden or bioswale that catches and filters runoff.Open guide →
derived roles
AI = read by an AI vision model · DERIVED = a computed estimate, not a direct measurement. The “How we know this” section below details each.
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 · Mar — USDA PLANTS (DwCA, Zenodo 17903503) — BloomPeriod
When to sow · for your area

Sow timing keys off your local last- and first-frost dates.

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 ~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:

Asymmetrura matutella Eurois occulta · Great Brocade Euxoa auxiliaris · Army Cutworm Moth Hedya separatana · Pink-Washed Leafroller Heliothis phloxiphaga · Darker-Spotted Straw Moth Mamestra configurata · Bertha Armyworm
+ 8 more species →
Mamestra curialis · Scripted Arches Megalographa biloba · owlet moth Papaipema cataphracta · Burdock Borer Papaipema nebris · Stalk Borer Polychrysia esmeralda · owlet moth Polychrysia moneta · Golden Plusia Polychrysia morigera · owlet moth Pyrrhia umbra · Bordered Sallow
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 7 bee visitors
Visitor records (observations, not exhaustive) from Noori et al. 2026 (CC BY 4.0) · GloBI →
Wildlife & visitors 2 nectaring

Open records of who else uses Sierra Larkspur — a generalist food-web signal, kept separate from the keystone Ecological Value.

2 adult butterfly & moth species are recorded nectaring at its flowers:

Papilio rutulus · Western Tiger Swallowtail Hyles lineata · White-Lined Sphinx
Interaction records (observations, not exhaustive) from GloBI → (CC0). Counts are distinct species; names are the most-recorded. Common names from Wikidata (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 (4) Methods & honest limits
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).
Climate niche (heat tolerance & native rainfall) Derived

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.

Realized-niche / climate-envelope approach (Pearson & Dawson 2003; Soberón 2007). Climate: NOAA NCEI nClimDiv county normals (1991–2020).
Mature width Derived

For woody plants that have a height but no measured crown, we estimate width = height × a crown-to-height ratio fit for that plant’s form (conifers narrower than broadleaf trees, shrubs widest), calibrated on our measured open-grown crowns and capped at the largest one ever measured. A measured crown always wins; herbaceous plants get nothing (no anchor).

Honest limits: A coarse class-median estimate for garden-scale spacing, not a measurement; woody single/multi-stem forms only.

Allometric basis: Jucker et al. 2022 (Tallo); Pretzsch et al. 2015; McPherson et al. 2016 (USDA Urban Tree DB).
Flower colour Derived

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.

McKenzie, P., Berardi, A.E., Hopkins, R. (2025). flower_color_phenology (MIT).
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 (35) 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)
[17] Invasive / introduced status — USDA PLANTS (DwCA, Zenodo 17903503) — native status
[18] Wetland indicator — USACE National Wetland Plant List (2022)
[20] Description — Wikipedia (CC BY-SA)
[21] Ecological value — Warren II 2026 (CC0) · Tallamy host-use counts
[22] Conservation rank — NatureServe Explorer (CC BY)
[24] Functional traits — TRY Plant Trait Database (CC BY 4.0)
[25] Photosynthetic pathway — TRY Plant Trait Database (CC BY 4.0)
[26] Climate niche — Derived — realized climate niche from U.S. county occurrences (GBIF) × NOAA NCEI county climate normals 1991–2020 (public domain)
[27] Wildlife & visitors — GloBI — Global Biotic Interactions (CC0)
[32] Flower-visitor value (derived) — Noori et al. 2026 (CC BY 4.0) · GloBI
[33] Caterpillar host count — Warren II 2026 (Dryad, CC0) · Tallamy host-use counts
[34] Caterpillar species — NHM HOSTS (CC0)
[35] County range — GBIF Open Data — open-licensed occurrences (CC0/CC-BY) → county
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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