Take a walk in Seattle’s urban oasis, Washington Park Arboretum, on a guided tour featuring the blooms and scents of the Witt Winter Garden. The tours, at 1 p.m. on Sundays from Graham Visitors Center, 2300 Arboretum Drive E., Seattle, will feature a selection of “Our Favorite Plants’’ from the tour guides. Walks are free and no registration is necessary, but call first to check that the walk is scheduled, since events are occasionally canceled (206-543-8800 or uwbotanicgardens.org).