The ultimate derivation is uncertain, with several theories presented in reference works. Some of the main theories:
Appears to be derived from a compound, possibly矢(ya,“arrow”) +な(na,Old Japaneseapophonic form of possessive particleの(no)) +木(ki,“tree”).[1] Theki changes togi as an instance ofrendaku (連濁).
As with many terms that name organisms, this term is oftenspelled inkatakana, especially inbiological contexts (where katakana is customary), asヤナギ(yanagi). As a hanafuda term, it is typically written in kanji, as 柳.
In some compounds,yanagi becomesyagi. See that entry for fuller details:やぎ.