球根
きゅうこん · kyuukon · JLPT N1 · noun
bulb
🌷 球 ball + 根 root = round root: a plant's underground storage ball
球 means ball or sphere and 根 means root. A bulb is a round underground storage organ, so the compound matches both its shape and its job.
球 — jade radical 玉/王 + qiu 求 (phonetic)
球 is a semantic-phonetic compound. The left side 王 is the 'jade' radical, indicating the original meaning: a fine piece of jade or a jade ornament. The right side 求 supplies the sound 'qiu'. Over time the meaning broadened from a jade sphere to any round object, and today it most commonly means 'ball' or 'globe'.
根 — tree radical 木 + 艮 (phonetic)
根 is a semantic-phonetic compound. The left side 木 ('tree') gives the meaning, since the character originally referred to the roots of a tree. The right side 艮 supplies the sound. From 'tree root' it extended to mean 'root, base, foundation' in general.