pod, hull, husk, shell, case
莢 centers on the protective outer covering of seeds or fruit: a pod, hull, husk, shell, or case that encloses something.
莢 combines the plant radical 艹 with 夾, which likely contributes the sound and the idea of something enclosing or pinching, like a pod holding seeds.
The plant top 艹 sits above 夾, which looks like a person with something tucked under each arm. Picture a plant whose seed pods are held tightly like items squeezed under the arms.
For キョウ, imagine a pod that makes a crisp 'kyow' sound when you snap it open: kyow -> キョウ, and the pod splits to reveal the seeds inside.
cartridge case
pod (e.g. a pea pod); shell; hull
ejection (of spent shell casings)
ejector tube; ejector housing (revolver)
Wright viburnum (viburnum wrightii)
honey locust (Gleditsia japonica)
spent shell casing; empty cartridge
(bacterial) capsule
legume; legumen; leguminous plant
green beans; French beans; string beans