Jack o'lantern Omphalotus illudens Gilled Mushrooms
Jack-In-The-Pulpit/ Indian-Turnip Arisaema triphyllum Arum/Calla
Jerusalem Artichoke Helianthus tuberosus Sunflower-Like
Jerusalem Oak Chenopodium botrys Goosefoot
Jewelweed, Pale/ Pale Touch-Me-Not Impatiens pallida Touch-Me-Not
Jewelweed, Spotted/ Spotted Touch-Me-Not Impatiens capensis Touch-Me-Not
Jimsonweed/ Thorn-Apple Datura stramonium Tomato/Nightshade
Joe Pye weed, spotted Eupatorium maculatum Composite
Joe-Pye-Weed, Hollow Eupatorium fistulosum Joe-Pye-Weed-Like
Joe-Pye-Weed, Sweet/ Green-Stemmed Joe-Pye-Weed Eupatorium purpureum Joe-Pye-Weed-Like
Johnny-Jump-Up/ Heartsease Viola tricolor Violet
Jumpweed (see Knotweed Virginia/ Jumpseed)
Juneberry, Downy (see Serviceberry)