Quick answer: 4 species in the register match "Monarch host plants", 4 with a live listing as of 16 Sep 2026.
All 4 species
Each entry links to the plant's profile with its native states and buying note.
- Antelope-horns milkweed Asclepias asperula · 2 states
- Butterflyweed Asclepias tuberosa · 37 states
- Swamp milkweed Asclepias incarnata · 25 states
- Whorled milkweed Asclepias verticillata · 6 states