pompelmoose, canque
椵 is a rare kanji with unclear standalone meaning. The given glosses "pompelmoose" (an old name for grapefruit) and "canque" (a type of citrus fruit) suggest it refers to a specific fruit tree, but the exact identity is uncertain.
椵 combines 木 (tree) with 叚, which likely contributes a phonetic element. The exact historical development is uncertain, and the character is rare in modern Japanese.
The left side 木 suggests a tree. The right side 叚 looks like a complex fruit with a protective covering. Picture a rare citrus tree bearing large, bumpy fruits like grapefruit.
For カ, imagine a car (カ) driving through a citrus orchard, the trees laden with pompelmoose. The car sound cues カ while the tree 木 reminds you of the fruit tree.