abura-gaya; Scirpus wichurai
A species of sedge native to East Asia. The name is usually written in kana.
Abura-gaya is a plant that grows in wetlands.
Katakana spelling is common for this plant name; usually written in kana.
Kanji spelling using 茅 (miscanthus/reed); rarely used.
Kanji spelling using 萱 (sedge/reed); rarely used.
The name likely derives from 油 (abura, 'oil') and 茅/萱 (kaya, 'reed' or 'sedge'), but the exact origin is uncertain.