Plants: P
- Poke Milkweed Asclepias exaltata
- Polyanthus Primrose Primula × polyantha Garden perennial
- Pomegranate Punica granatum Tree fruit
- Pomelo Citrus maxima Tree fruit
- Poppy Anemone Anemone coronaria Garden perennial
- Possumhaw Ilex decidua Flowering shrub
- Possumhaw Viburnum Viburnum nudum Flowering shrub
- Potato Solanum tuberosum Root
- Potato Vine Solanum jasminoides Vine
- Powderpuff Mimosa strigillosa Creeping perennial
- Powderpuff Tree Calliandra haematocephala Flowering shrub
- Powdery Thalia Thalia dealbata Garden perennial
- Praestans Tulip Tulipa praestans Bulb
- Prairie Blazing Star Liatris pycnostachya Wildflower
- Prairie Coreopsis Coreopsis palmata Wildflower
- Prairie Crabapple Malus ioensis Flowering tree
- Prairie Dock Silphium terebinthinaceum Wildflower
- Prairie Dropseed Sporobolus heterolepis Grass sedge
- Prairie Ironweed Vernonia fasciculata Wildflower
- Prairie Junegrass Koeleria macrantha Grass sedge
- Prairie Milkweed Asclepias sullivantii Wildflower
- Prairie Nymph Herbertia lahue Bulb
- Prairie Onion Allium stellatum Wildflower
- Prairie Parsley Polytaenia nuttallii Wildflower
- Prairie Phlox Phlox pilosa Wildflower
- Prairie Rose Rosa setigera Flowering shrub
- Prairie Smoke Geum triflorum Garden perennial
- Prairie Sunflower Helianthus petiolaris Wildflower
- Prairie Verbena Glandularia bipinnatifida Creeping perennial
- Prairie Wild Rose Rosa arkansana Flowering shrub
- Prairie Willow Salix humilis Wildflower
- Prairie Zinnia Zinnia grandiflora Wildflower
- Preston Lilac Syringa × prestoniae Flowering shrub
- Prettyface Triteleia ixioides Wildflower
- Pride of Barbados Caesalpinia pulcherrima Flowering shrub
- Pride of Madeira Echium candicans Flowering shrub
- Primrose Jasmine Jasminum mesnyi Flowering shrub
- Prince's Plume Stanleya pinnata Wildflower
- Princess Flower Tibouchina urvilleana Flowering shrub
- Prostrate Acacia Acacia redolens Creeping perennial
- Prostrate Speedwell Veronica prostrata Creeping perennial
- Puget Sound Gumweed Grindelia integrifolia
- Pumpkin Cucurbita maxima Fruiting
- Purple Angelica Angelica gigas Wildflower
- Purple Bell Vine Rhodochiton atrosanguineus Vine
- Purple Bergamot Monarda media Wildflower
- Purple Coneflower Echinacea purpurea Wildflower
- Purple Giant Hyssop Agastache scrophulariifolia Wildflower
- Purple Heart Tradescantia pallida Creeping perennial
- Purple Lovegrass Eragrostis spectabilis Grass
- Purple Milkweed Asclepias purpurascens Wildflower
- Purple Mullein Verbascum phoeniceum Wildflower
- Purple Needlegrass Nassella pulchra Grass
- Purple Owl's Clover Castilleja exserta Wildflower
- Purple Passion Asparagus Asparagus officinalis Fruiting
- Purple Prairie Clover Dalea purpurea Wildflower
- Purple Rockrose Cistus × purpureus Flowering shrub
- Purple Sage Salvia dorrii Flowering shrub
- Purple Toadflax Linaria purpurea Wildflower
- Purple-Flowering Raspberry Rubus odoratus Flowering shrub
- Purplehead Sneezeweed Helenium flexuosum Wildflower
- Purpleosier Willow Salix purpurea
- Purplestem Angelica Angelica atropurpurea Wildflower
- Purplestem Aster Symphyotrichum puniceum Wildflower
- Purpletop Tridens flavus Grass sedge
- Purpletop Vervain Verbena bonariensis Garden perennial
- Purslane Portulaca oleracea Leafy
- Pussy Willow Salix discolor Flowering shrub