The word madderworts is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 19
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (53 words)
adorers, armored, armrest, arrowed, darters, deodars, deworms, dormers, dotards, drawers, drowsed, madders, maddest, madwort, maestro, marrows, meadows, mortars, radomes, ramrods, redraws, reroast, reswarm, retards, rewards, rewarms, rewords, roamers, roasted, roaster, rodders, seaworm, smarted, smarter, stardom, starred, steward, stormed, strawed, strowed, swarded, swarmed, swarmer, sworded, tarrows, towards, traders, tremors, wadders, warders, warmers, warmest, wormers