Tree · Sonoran native
Feather Bush
Lysiloma watsonii · Fabaceae
Also called: Feather Tree, Littleleaf Feather Bush, Desert Fern, Tepeguaje (regional)
Feather Bush (Lysiloma watsonii) is a low-water tree native to the Sonoran Desert region well suited to Tucson and the low desert. It thrives in full sun to partial shade.
Feather Bush at a glance
- Water use
- Low (established)
- Sun
- Full sun to partial shade.
- Mature size
- 12-15 ft H x 12-15 ft W (sometimes to 20 ft; multi-trunk small tree).
- Growth rate
- Moderate to fast (with summer water).
- Bloom
- Creamy white, fluffy puffball flowers., Late spring into summer (May-July), followed by flat brown seedpods.
- Cold hardiness
- Cold sensitive: hardy to about 20-25 F; USDA zones 9-11. May suffer frost dieback in cold Tucson winters but recovers; foliage drops in cold.
- Soil
- Adaptable; prefers well-drained soils but tolerates a range of native desert soils. As a legume, it fixes nitrogen and thrives in lean soil.
- Native range
- Native to the Sonoran Desert and thornscrub of southern Arizona (notably the Rincon and Santa Catalina foothills) and Sonora, Mexico.
- Best used as
- Filtered-shade patio tree, Ornamental specimen (fern-like foliage), Native and habitat garden, Small accent tree
- Wildlife
- Flowers attract bees, butterflies, and other pollinators; legume seeds and foliage provide some wildlife value; nitrogen-fixing improves soil for surrounding plants.
- Toxicity
- No significant toxicity reported (Lysiloma species are not noted as toxic in landscape use).
How to grow Feather Bush in Tucson & the low desert
Watering
Drought tolerant once established; deep, infrequent irrigation (every 1-2 weeks in summer heat) keeps the canopy full and lush. Drops leaflets under drought or cold stress.
Fertilizer & nutrients
Generally none needed; as a nitrogen-fixing legume it makes its own nitrogen. Avoid fertilizing.
Pruning & care
Prune in spring after frost danger has passed to remove cold-damaged wood and develop a tree form. Thin to lighten the canopy and reduce wind resistance. Wait until warm weather to assess freeze damage before cutting.
Notes
Botanical name often listed under the synonym Lysiloma microphylla var. thornberi; the accepted Arizona name is Lysiloma watsonii. Prized for delicate, ferny, bipinnate foliage casting light dappled shade. Semi-evergreen to deciduous depending on winter cold. Best in warm microclimates in Tucson due to frost sensitivity.
Sources: Arizona-Sonora Desert Museum; University of Arizona Cooperative Extension; AMWUA Landscape Plants for the Arizona Desert; Tohono Chul Park