common ragweed; annual ragweed
A common weed in Japan, notorious for causing hay fever. The scientific name is Ambrosia artemisiifolia.
In autumn, ragweed pollen flies around and I can't stop sneezing.
Katakana spelling is standard for this plant name; usually written in kana.
Kanji spelling is rare and mainly used in botanical contexts; learners will almost always encounter the katakana form.
Compound of 豚 (buta, 'pig') and 草 (kusa, 'grass/weed'), literally 'pig weed'. The exact origin of the name is uncertain, but it may refer to the plant's use as pig feed or its coarse appearance.