river ginger tree, oleaster
茱 refers to specific aromatic plants: the river ginger tree and the oleaster. Its meaning is narrow and botanical, without a broad abstract core.
茱 combines the plant radical 艹 with 朱, which likely contributes a phonetic element. The character is used for specific plant names.
The grass top 艹 marks this as a plant, and the bottom 朱 (vermillion) hints at the reddish berries of the oleaster or the aromatic quality of river ginger. Picture a vermillion-tinged plant used for its fragrance.
For シュ, imagine a shoe-shaped leaf on the plant: shoe -> シュ, and you pick the aromatic leaf to put in your shoe for a fresh scent.
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Elaeagnus multiflora var. hortensis (variety of goumi)
Tetradium ruticarpum (species of deciduous trees)
Elaeagnus multiflora var. hortensis (variety of goumi)
goumi (species of oleaster, Elaeagnus multiflora); cherry silverberry
Asiatic dogwood (Cornus officinalis); Japanese cornel; Japanese cornelian-cherry
autumn olive (Elaeagnus umbellata); Japanese silverberry; oleaster
silverthorn (species of oleaster, Elaeagnus pungens); thorny elaeagnus; thorny olive