Quick answer: 30 native Maryland plants have a recorded bloom range that includes August.
30 species
- Black-eyed Susan Rudbeckia hirta · 42 states
- Blue mistflower Conoclinium coelestinum · 26 states
- Butterflyweed Asclepias tuberosa · 37 states
- Cardinal flower Lobelia cardinalis · 37 states
- Common buttonbush Cephalanthus occidentalis · 23 states
- Common yarrow Achillea millefolium · 31 states
- Crimson-eyed rose-mallow Hibiscus moscheutos · 14 states
- Dense blazing star Liatris spicata · 15 states
- Devil's walking stick Aralia spinosa · 14 states
- Eastern purple coneflower Echinacea purpurea · 22 states
- Great blue lobelia Lobelia siphilitica · 32 states
- Great laurel Rhododendron maximum · 13 states
- Hollow Joe-pye weed Eutrochium fistulosum · 14 states
- Indian blanket Gaillardia pulchella · 18 states
- Maypop passionflower Passiflora incarnata · 13 states
- New England aster Symphyotrichum novae-angliae · 18 states
- New Jersey tea Ceanothus americanus · 31 states
- Scarlet beebalm Monarda didyma · 18 states
- Seaside alder Alnus maritima · 2 states
- Smooth hydrangea Hydrangea arborescens · 12 states
- Smooth sumac Rhus glabra · 34 states
- Sourwood Oxydendrum arboreum · 14 states
- Spotted beebalm Monarda punctata · 14 states
- Swamp azalea Rhododendron viscosum · 7 states
- Swamp milkweed Asclepias incarnata · 25 states
- Swamp sunflower Helianthus angustifolius · 15 states
- Sweet-fern Comptonia peregrina · 10 states
- Trumpet vine Campsis radicans · 24 states
- White snakeroot Ageratina altissima · 7 states
- Winged sumac Rhus copallinum · 11 states