Littleleaf Horsebrush Tetradymia glabrata
Littleleaf Horsebrush is a perennial shrub native to the lower 48 states. It grows to 12 ft and blooms Aug in part shade – shade, with brown fruit. A host for pollen-specialist native bees.
Growing & care
USDA PLANTS · TRY- Sun
- Part shade – shade
- Soil & moisture
- Low moisture
- Soil pH
- 7–8
- Fertility need
- Low
- Adapts to
- Coarse (sandy), Medium (loam)
- Hardiness
- USDA zone 6+
- Height
- 12 ft
- Mature width
- ~ 10 ft wide DERIVED derived estimate — open-grown crown allometry (height × growth-form ratio); not a measurement
- Spacing
- 17–21 ft apart from USDA planting density
- Spread
- None — clumping
- Growth rate
- Slow
- Growth form
- Multiple stems
- Lifespan
- Perennial · moderate
- Foliage
- Broadleaf · fine texture
- Active growth
- Spring through autumn
- Fruit
- Brown persists into winter
- Flower colour
- Yellow AI AI image-analysis of community-science photos (~87% expert agreement) — not a botanical record
- Propagate by
- Seed, Cuttings, Bare root, Container
- Seed starting
- No stratification needed
- Seeds ripen
- Autumn – Winter seed-collection / harvest window
- In the trade
- No known commercial source
- Deer browsing
- Low often deer-resistant
- Resprouts if cut
- Yes regrows after top-kill
Sow timing keys off your local last- and first-frost dates.
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Tetradymia in North America, including:
✦ Bees specialist-bee host · 2 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. Tetradymia is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
2 native & managed bee species are documented visiting Littleleaf Horsebrush :
Across 88 U.S. vegetation-survey plots that recorded Littleleaf Horsebrush, these catalog species turned up most often in the same plot — a real field co-occurrence signal, not a planting prescription.
Related plants
More Tetradymia →
How we know this (3) 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.
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.
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 (31) 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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