Cork elm
Ulmus thomasii
Last reviewed: September 2026

Toxicity unknown
Cork elm (Ulmus thomasii) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
medium
Size
480"–840" H × 300"–480" W
Bloom
Mar, Apr
Native to
AR, IA, IL, IN and 15 more states
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.
Find rebates in your areaBrowse plants for this ecoregion
A tall, upright tree with a narrow, vase-like crown, corky-ridged branches, and doubly-toothed leaves that turn yellow in fall.
Wildlife value
Host plant for question mark, eastern comma.
Foliage is a larval host for question mark and eastern comma butterflies, and the tree's structure provides valuable nesting habitat for birds.
Common questions
- How much sun does Cork elm need?
- Cork elm grows best in full sun conditions.
- When does Cork elm bloom?
- Cork elm blooms in March and April.
- Where is Cork elm native?
- Cork elm (Ulmus thomasii) is native to AR, IA, IL, IN and 15 more states, per the World Checklist of Vascular Plants (Kew).
- What butterflies or moths does Cork elm host?
- Cork elm is a larval host plant for question mark and eastern comma.
Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Ready to grow Cork elm? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Planning a bed around it? Start a free plan with this plant
Not sure where to start? Take the 2-minute yard quiz