horsefly weed(n = noun.plant) baptisia tinctoria, indigo broom, rattle weed - much-branched erect herb with bright yellow flowers; distributed from Massachusetts to Florida;
is a kind of false indigo, wild indigo
ague weed, alligator weed, butterfly weed, cancer weed, consumption weed, crazy weed, devil's weed, dill weed, dyer's weed, french weed, ghost weed, horsefly, jamestown weed, jimson weed, joe-pye weed, klammath weed, mad-dog weed, orchilla weed, pickerel weed, pineapple weed, polecat weed, rattle weed, rattlesnake weed, rheumatism weed, scorpion weed, spotted joe-pye weed, stemless golden weed, stinking weed, styptic weed, trumpet weed, turpentine camphor weed, turpentine weed, weed, weed killer, weed out