The word houseplant 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: 18
Highest Scoring Words With Friends™ Play In The Letters houseplant
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Seven Letter Word Alert: (24 words)
apostle, apthous, eluants, ethanol, housane, leantos, leptons, loathes, lunates, nepotal, opulent, outleap, outplan, outspan, peanuts, penults, phenols, planets, plutons, pulsate, taphole, teashop, unleash, upslant