stip·ule /ˈstɪ(ˌ)pju(ə)l/
  托葉
  Stip·ule n.  Bot. An appendage at the base of petioles or leaves, usually somewhat resembling a small leaf in texture and appearance.
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  stipule
       n : a small leafy outgrowth at the base of a leaf or its stalk;
           usually occurring in pairs and soon shed