Quick answer: 76 native Louisiana plants have a recorded bloom range that includes May.
76 species
- American beautyberry Callicarpa americana · 10 states
- American beech Fagus grandifolia · 24 states
- American holly Ilex opaca · 24 states
- American hornbeam Carpinus caroliniana · 29 states
- American olive Osmanthus americanus · 4 states
- American wisteria Wisteria frutescens · 14 states
- Birdfoot violet Viola pedata · 14 states
- Black cherry Prunus serotina · 32 states
- Black locust Robinia pseudoacacia · 12 states
- Black walnut Juglans nigra · 33 states
- Black willow Salix nigra · 2 states
- Butterflyweed Asclepias tuberosa · 37 states
- Cardinal flower Lobelia cardinalis · 37 states
- Carolina allspice Calycanthus floridus · 5 states
- Carolina jessamine Gelsemium sempervirens · 9 states
- Clasping coneflower Dracopis amplexicaulis · 2 states
- Common elderberry Sambucus nigra ssp. canadensis · 16 states
- Common persimmon Diospyros virginiana · 17 states
- Common yarrow Achillea millefolium · 31 states
- Coral honeysuckle Lonicera sempervirens · 16 states
- Coralberry Symphoricarpos orbiculatus · 20 states
- Crossvine Bignonia capreolata · 5 states
- Downy serviceberry Amelanchier arborea · 34 states
- Eastern bluestar Amsonia tabernaemontana · 8 states
- Eastern hop-hornbeam Ostrya virginiana · 18 states
- Eastern purple coneflower Echinacea purpurea · 22 states
- Eastern red cedar Juniperus virginiana · 36 states
- Eastern redbud Cercis canadensis · 30 states
- Farkleberry Vaccinium arboreum · 5 states
- Flowering dogwood Cornus florida · 22 states
- Green ash Fraxinus pennsylvanica · 23 states
- Honey locust Gleditsia triacanthos · 9 states
- Indian blanket Gaillardia pulchella · 18 states
- Indigo bush Amorpha fruticosa · 16 states
- Lanceleaf coreopsis Coreopsis lanceolata · 28 states
- Lemon beebalm Monarda citriodora · 15 states
- Loblolly bay Gordonia lasianthus · 5 states
- Lyreleaf sage Salvia lyrata · 2 states
- Mexican hat Ratibida columnifera · 17 states
- Mountain witch-alder Fothergilla major · 7 states
- Northern catalpa Catalpa speciosa · 9 states
- Northern spicebush Lindera benzoin · 16 states
- Pale purple coneflower Echinacea pallida · 9 states
- Pawpaw Asimina triloba · 17 states
- Pink evening primrose Oenothera speciosa · 8 states
- Plains coreopsis Coreopsis tinctoria · 16 states
- Possumhaw Ilex decidua · 7 states
- Post oak Quercus stellata · 9 states
- Red buckeye Aesculus pavia · 9 states
- Red chokeberry Aronia arbutifolia · 7 states
- Roughleaf dogwood Cornus drummondii · 3 states
- Royal fern Osmunda regalis var. spectabilis · 8 states
- Sassafras Sassafras albidum · 22 states
- Shumard oak Quercus shumardii · 5 states
- Silky camellia Stewartia malacodendron · 2 states
- Smooth hydrangea Hydrangea arborescens · 12 states
- Smooth sumac Rhus glabra · 34 states
- Sourwood Oxydendrum arboreum · 14 states
- Southern crabapple Malus angustifolia · 2 states
- Southern live oak Quercus virginiana · 13 states
- Southern magnolia Magnolia grandiflora · 10 states
- Southern red oak Quercus falcata · 6 states
- Standing cypress Ipomopsis rubra · 6 states
- Stokes aster Stokesia laevis · 4 states
- Sweetgum Liquidambar styraciflua · 22 states
- Titi cyrilla Cyrilla racemiflora · 5 states
- Two-wing silverbell Halesia diptera · 5 states
- Virginia creeper Parthenocissus quinquefolia · 27 states
- Virginia iris Iris virginica · 9 states
- Virginia sweetspire Itea virginica · 6 states
- Water oak Quercus nigra · 4 states
- White fringetree Chionanthus virginicus · 14 states
- White oak Quercus alba · 33 states
- Willow oak Quercus phellos · 16 states
- Woodland pinkroot Spigelia marilandica · 4 states
- Yaupon holly Ilex vomitoria · 7 states