1The buckwheat plant itself—the crop (Fagopyrum esculentum) used to make buckwheat flour; usually written in kana as そば.
秋になるとそばの花が白く咲く。
In autumn, buckwheat flowers bloom white.
この地方はそばの栽培が盛んだ。
This region is active in cultivating buckwheat.
2Soba noodles (Japanese buckwheat noodles made from buckwheat flour), as in zaru-soba or kake-soba; commonly written in kana そば.
昼ごはんにざるそばを食べた。
I ate zaru-soba for lunch.
寒い日は温かいそばがほっとする。
On cold days, hot soba is comforting.
立ち食いそばは忙しい人に人気がある。
Standing soba shops are popular with busy people.
3Can also refer to Chinese-style wheat noodles (e.g. chūka-soba); in some regions or shops, そば may mean ramen-like noodles.
あの店の中華そばは昔ながらの味で人気だ。
That shop's chūka-soba has a traditional taste and is popular.
地方によってはラーメンを『そば』と呼ぶことがある。
In some regions, ramen is called 'soba'.