Tsukushi rhododendron
A variety of Rhododendron metternichii native to the Tsukushi region (northern Kyushu). Botanical term; in everyday contexts, usually referred to by the katakana name.
Tsukushi rhododendron grows wild in the mountains of northern Kyushu.
I planted a Tsukushi rhododendron in the garden.
General term for rhododendron; ツクシシャクナゲ is a specific regional variety.
Katakana spelling is common for plant names and is the usual written form for this word.
Kanji spelling is rare and mainly found in botanical or historical contexts.
From 筑紫 (Tsukushi, an old name for the region of northern Kyushu) + 石楠花 (shakunage, rhododendron). The exact derivation is straightforward; the plant is named after its native region.