発芽
はつが · hatsuga · JLPT N1 · noun
germination
🌱 発 = emerge + 芽 = sprout/bud: germination is a sprout emerging from a seed
芽 is the sprout or bud a plant puts out, and 発 means to emerge or set off. Joined, they name the moment a seed first pushes out its sprout.
芽 — grass radical 艹 + tooth 牙 (phonetic)
芽 is a semantic-phonetic compound. The grass radical 艹 on top signals plants, while 牙 ('tooth') below provides the sound 'ya'. The original sense is the tender sprout or shoot pushing up from a seed, like a small tooth emerging from the soil.