Giant Woollystar Eriastrum densifolium
Giant Woollystar is a perennial shrub native to the lower 48 states. It grows to 3 ft and blooms May – Aug. A host for pollen-specialist native bees.
More about this plant
Eriastrum densifolium is a species of flowering plant in the phlox family known by the common name giant woollystar. This wildflower is native to California and Baja California where it grows in open areas such as sand dunes and dry washes. It grows on an erect stem with slightly hairy to densely woolly foliage, often giving the plant a dark gray-green color. The leaves are narrow and spike-shaped with pointed lobes. The top of each stem is occupied by a bunched inflorescence full of woolly leaflike bracts and funnel-shaped, flat-faced flowers. The flowers are each 1 to 3 centimeters long with a face up to three or four centimeters wide. The lobes are white to bright, striking blue, sometimes with longitudinal pinstripes. The stamens protrude from the throat. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 11 derived from its U.S. range
- Height
- 3 ft
- Lifespan
- Perennial
- Flower colour
- Blue AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Eriastrum in North America, including:
✦ 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. Eriastrum 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 Giant Woollystar :
Wildlife & visitors 21 nectaring
Open records of who else uses Giant Woollystar — a generalist food-web signal, kept separate from the keystone Ecological Value.
21 adult butterfly & moth species are recorded nectaring at its flowers — the most-recorded:
Related plants
More Eriastrum →
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 (20) 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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