Bicknell's Cranesbill Geranium bicknellii
Bicknell's Cranesbill is an annual wildflower native to Canada and the lower 48 states. It blooms May – Aug. A host for pollen-specialist native bees.
More about this plant
Geranium bicknellii is a species of geranium known by the common names Bicknell's cranesbill and northern cranesbill. It is native to much of the northern half of North America, where it can be found in a number of forest and woodland habitats. This is an annual or biennial herb which grows hairy stems up to about half a meter long. It may be erect or lie near the ground. Each leaf is several centimeters long and wide and is divided into several lobes, each of which may have smaller lobes or teeth. Flowers grow singly or in pairs and have pointed sepals and small lavender petals, each with a notch in the tip. The fruit has a rounded body with a long, straight style about 2 centimeters in length and tipped with a small beak. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 4 derived from its U.S. range
- Lifespan
- Annual
- Foliage
- Broadleaf
- Flower colour
- Pink AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts ~24 caterpillar species
Geranium supports ~24 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 Geranium in North America, including:
+ 8 more species → ↑ show fewer
✦ Bees specialist-bee host · 5 bee visitors
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Geranium is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
5 native & managed bee species are documented visiting Bicknell's Cranesbill :
Related plants
More Geranium →
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 (21) 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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