Quick answer: 20 native Illinois plants have a recorded bloom range that includes March.
20 species
- American sycamore Platanus occidentalis · 24 states
- Black cherry Prunus serotina · 32 states
- Bloodroot Sanguinaria canadensis · 9 states
- Bur oak Quercus macrocarpa · 24 states
- Canada wild rye Elymus canadensis · 18 states
- Common blue violet Viola sororia · 21 states
- Eastern red cedar Juniperus virginiana · 36 states
- Eastern red columbine Aquilegia canadensis · 36 states
- Eastern redbud Cercis canadensis · 30 states
- Jack-in-the-pulpit Arisaema triphyllum · 14 states
- Mayapple Podophyllum peltatum · 18 states
- New Jersey tea Ceanothus americanus · 31 states
- Ohio buckeye Aesculus glabra · 12 states
- Quaking aspen Populus tremuloides · 24 states
- Shagbark hickory Carya ovata · 22 states
- Smooth Solomon's seal Polygonatum biflorum · 13 states
- Virginia bluebells Mertensia virginica · 14 states
- White oak Quercus alba · 33 states
- Wild blue Phlox divaricata · 32 states
- Wild geranium Geranium maculatum · 11 states