Quick answer: 41 native Arizona plants have a recorded bloom range that includes May.
41 species
- Alderleaf mountain mahogany Cercocarpus montanus · 9 states
- Anderson wolfberry Lycium andersonii · 1 states
- Antelope-horns milkweed Asclepias asperula · 2 states
- Apache plume Fallugia paradoxa · 6 states
- Arizona rosewood Vauquelinia californica · 1 states
- Banana yucca Yucca baccata · 6 states
- Beavertail prickly pear Opuntia basilaris · 1 states
- Buffalograss Bouteloua dactyloides · 9 states
- Butterflyweed Asclepias tuberosa · 37 states
- California buckwheat Eriogonum fasciculatum · 2 states
- Cardinal flower Lobelia cardinalis · 37 states
- Chokecherry Prunus virginiana · 35 states
- Chuparosa Justicia californica · 1 states
- Common sotol Dasylirion wheeleri · 3 states
- Creeping Oregon grape Mahonia repens · 11 states
- Creosote bush Larrea tridentata · 5 states
- Desert globemallow Sphaeralcea ambigua · 2 states
- Desert marigold Baileya multiradiata · 4 states
- Desert willow Chilopsis linearis · 4 states
- Eastern redbud Cercis canadensis · 30 states
- Engelmann's hedgehog cactus Echinocereus engelmannii · 1 states
- Fairy duster Calliandra eriophylla · 1 states
- Firecracker penstemon Penstemon eatonii · 3 states
- Gambel oak Quercus gambelii · 6 states
- Indian blanket Gaillardia pulchella · 18 states
- Jojoba Simmondsia chinensis · 2 states
- Joshua tree Yucca brevifolia · 3 states
- New Mexico locust Robinia neomexicana · 2 states
- Ocotillo Fouquieria splendens · 3 states
- Old man's whiskers Geum triflorum · 8 states
- Palmer's penstemon Penstemon palmeri · 3 states
- Prairie Junegrass Koeleria macrantha · 15 states
- Quaking aspen Populus tremuloides · 24 states
- Red barberry Mahonia haematocarpa · 1 states
- Rocky Mountain bee plant Peritoma serrulata · 22 states
- Rocky Mountain iris Iris missouriensis · 7 states
- Saguaro Carnegiea gigantea · 1 states
- Smooth sumac Rhus glabra · 34 states
- Utah sweetvetch Hedysarum boreale · 3 states
- Winterfat Krascheninnikovia lanata · 6 states
- Yellow bells (esperanza) Tecoma stans · 3 states