Chinese hibiscus; Hibiscus rosa-sinensis
Refers specifically to the tropical flowering shrub Hibiscus rosa-sinensis, commonly called hibiscus. The name is usually written in katakana.
A Chinese hibiscus is blooming in the garden.
You often see Chinese hibiscus in Okinawa.
ハイビスカス is the more common, general term for hibiscus in Japanese, while ブッソウゲ is a specific, somewhat botanical name for Hibiscus rosa-sinensis.
Katakana spelling is standard for this plant name; usually written in kana.
Ateji kanji form; rarely used in modern writing.
Variant ateji kanji form; rarely used.
The reading ぶっそうげ likely derives from a Chinese term for the plant, but the exact origin is uncertain. The kanji 仏桑花/仏桑華 are ateji.