⚠️ Noxious Weeds
Noxious weeds are plants that can harm agriculture, natural areas or human health. In Ontario, the 25 weeds below are designated as noxious under the Weed Control Act. Click a weed’s name to see photos and identification information.
🧤 Take care: giant hogweed, wild parsnip, poison-hemlock and poison-ivy can cause serious skin burns, rashes or poisoning. Don’t touch them with bare skin. Wear gloves, long sleeves and eye protection, or contact your municipality for help with removal.
Ontario’s Noxious Weeds
| Common Name (click for photos & info) | Botanical Name |
|---|---|
| Common Barberry | Berberis vulgaris |
| Smooth Bedstraw | Galium mollugo |
| European Buckthorn | Rhamnus cathartica |
| Wild Chervil | Anthriscus sylvestris |
| Coltsfoot | Tussilago farfara |
| Common Crupina | Crupina vulgaris |
| Woolly Cupgrass | Eriochloa villosa |
| Dodder | Cuscuta spp. |
| Dog-strangling Vine | Vincetoxicum rossicum |
| Black Dog-strangling Vine | Vincetoxicum nigrum |
| Jointed Goatgrass | Aegilops cylindrica |
| Giant Hogweed ⚠️ | Heracleum mantegazzianum |
| Knapweed | Centaurea spp. |
| Kudzu | Pueraria montana |
| Wild Parsnip ⚠️ | Pastinaca sativa |
| Poison-hemlock ⚠️ | Conium maculatum |
| Poison-ivy ⚠️ | Toxicodendron radicans |
| Ragweed | Ambrosia spp. |
| Tansy Ragwort | Senecio jacobaea |
| Sow-thistle | Sonchus spp. |
| Cypress Spurge | Euphorbia cyparissias |
| Leafy Spurge | Euphorbia esula |
| Bull Thistle | Cirsium vulgare |
| Canada Thistle | Cirsium arvense |
| Serrated Tussock | Nassella trichotoma |
🌻 What to Plant Instead
After removing a noxious weed, replant the area with native plants so it doesn’t come back. See Plants for Monarch Award Gardens for ideas, and check our Invasive Plants page for other problem plants to watch for.