The grass radical 艹 is the top-of-plant form of 草. Its presence puts 茉 firmly in the botanical family alongside 花, 草 and 茶, signalling that this character names a flowering plant - jasmine.
Carries the sound mò unchanged into 茉. Its own image of a tree with a marker at the tip is incidental here - purely a phonetic loan that lets readers predict the pronunciation of 茉莉 (jasmine) at a glance.
