By James Hibberd
Updated June 27, 2011 at 09:02 PM EDT

Gossip Girl star Michelle Trachtenberg will guest star on Showtime’s Weeds, playing a rival to Mary-Louise Parker’s Nancy.

Trachtenberg will appear in two episodes of the Showtime comedy this season playing Emma, a low-level pot dealer who gets the attention of Silas (Hunter Parrish). The show’s seventh season begins tonight.