Flower profile
Be-still tree
Cascabela thevetia
Be-still tree (Cascabela thevetia) is a shrub or small tree in the Apocynaceae family, introduced in the lower 48 states.
Be-still tree is a flowering plant that USDA PLANTS lists as introduced in the lower 48 states.
*iNaturalist research-grade observations, as of October 17, 2026.
On our lists for: Hawaii
Quick look
Cascabela thevetia is a species of poisonous plant in the dogbane family Apocynaceae, native throughout Mexico and Central America and cultivated widely as an ornamental. It is a relative of Nerium oleander and thus is known by the common name yellow oleander.
- It belongs to the Apocynaceae family. iNaturalist
- USDA PLANTS describes it as a shrub / a tree with a perennial life cycle. USDA PLANTS
- USDA PLANTS lists it as introduced in the lower 48 states and records it in 3 states. USDA PLANTS
- iNaturalist has 500 research-grade sightings of it in Hawaii, ranking #98 among the 118 flowers on our Hawaii list. iNaturalist
When does it bloom?
There are only a handful of Hawaii flowering records, so this chart uses records from across the U.S.
Conservation status
- Federal (U.S. ESA)
- Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. USFWS ECOS
- NatureServe
- Unknown We couldn't find this name in NatureServe Explorer. NatureServe
- Hawaii
- Not listed Not on Hawaii threatened and endangered plants (HAR 13-107; the state list follows the federal list), DLNR Division of Forestry and Wildlife. HAR 13-107
Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.
Can you eat it?
NC State Extension lists it as poisonous to humans (severity: high). Poisonous parts: sap/juice. Symptoms they list: “All parts of the plant are poisonous if ingested and the sap can cause allergic skin reactions in some people. Smoke from burning plant material can be toxic.” They also note: “All parts of the plant are toxic.” NC State Extension
NC State Extension flags it as a problem for cats, dogs and horses. It isn't on the ASPCA plant list. NC State Extension
🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.
Where does it grow?
USDA PLANTS records be-still tree in 3 states.
recorded by USDA PLANTS on our state lists not recorded
See the full list of states
Florida, Hawaii, Texas.
Hawaii counties with USDA records: Honolulu, Kauai, Maui.
Names, range and relatives
Native status by region (USDA PLANTS): Hawaii: Introduced; Lower 48 states: Introduced; Pacific Basin (excluding Hawaii): Introduced; Puerto Rico: Introduced; U.S. Virgin Islands: Introduced.
Other scientific names (synonyms in USDA PLANTS): Cerbera thevetia, Thevetia neriifolia.
County records: USDA PLANTS lists it in 11 counties across 5 states; the most are in Texas (4), Hawaii (3), Florida (2).
More from the Apocynaceae family (28 on Bloomipedia; most observed first): Common milkweed, Butterfly milkweed, Lesser periwinkle, Swamp milkweed, Greater periwinkle, Green antelopehorns, Antelopehorn milkweed, Showy milkweed.
More Hawaii flowers
Sources
- USDA, NRCS. PLANTS Database, profile THPE3.
- iNaturalist, Cascabela thevetia: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
- Wikipedia, Cascabela thevetia (lead quoted under CC BY-SA 4.0).
- Hawaii: Hawaii threatened and endangered plants (HAR 13-107; the state list follows the federal list), DLNR Division of Forestry and Wildlife.
- Hawaii: Hawaii noxious weed list (HAR 4-68).
- USFWS, ECOS species database (ESA listing check), October 17, 2026.
- Edibility and toxicity: NC State Extension.
- Photo: stinger via iNaturalist · CC BY 4.0 · resized.