noun
Hydrangea macrophylla var. thunbergii; sweet hydrangea plant
Botanical name for a variety of bigleaf hydrangea whose leaves are used to make a sweet tea.
甘茶はアジサイの仲間で、葉を乾燥させてお茶にします。
Amacha is a type of hydrangea; its leaves are dried and made into tea.
noun
sweet hydrangea leaf tea; hydrangea tea
The sweet tea made from the leaves of the plant; traditionally served on Buddha's Birthday (花祭り).
花祭りでは甘茶が振る舞われます。
Sweet hydrangea tea is served at the Flower Festival.
この甘茶はほんのり甘くておいしい。
This hydrangea tea is mildly sweet and delicious.
アジサイ is the common hydrangea grown for ornamental flowers, while 甘茶 is a specific variety whose leaves are used for tea.
From 甘 (sweet) + 茶 (tea), referring to the sweet tea made from the leaves of this hydrangea variety.