The Houston Happy Hikers will host a noncompetitive walk in Mercer Arboretum & Botanic Gardens, 22306 Aldine-Westfield, Humble, 9 a.m.-noon Sat., April 22. Participants may walk, jog or run at any desired pace, starting anytime 9 a.m.-noon and finishing by 3 p.m. The walk area features three ponds and over 20 acres of gardens that include endangered plants. Walking trails are along packed gravel paths. Pets are not allowed. For more information, see www.houstonhappyhikers.com.