This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 芲 is uncertain. It visually contains 艹 (grass) and 仑, but the original semantic or phonetic role of these components is unclear.
The top grass radical 艹 suggests a plant, but the overall meaning is unclear. Imagine a mysterious plant with an unknown name.
For カ, picture a car driving through a field of this mysterious grass: car -> カ, and the car is surrounded by the unknown plant.