This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 蘛 is uncertain. It visually combines 艹 (grass), 甚, and 育, but the original semantic and phonetic roles are unclear.
With grass on top and 甚 beside 育, imagine a plant growing vigorously, but its exact meaning is unclear.
For イク, picture a plant that makes you say 'ick!' because it's overgrown: ick -> イク.