bi·en·ni·al /(ˌ)baɪˈɛniəl/
 二年生植物,二年一次的事(a.)二年生的,二年一次的
 Bi·en·ni·al a.
 1. Happening, or taking place, once in two years; as, a biennial election.
 2. Bot. Continuing for two years, and then perishing, as plants which form roots and leaves the first year, and produce fruit the second.
 Bi·en·ni·al, n.
 1. Something which takes place or appears once in two years; esp. a biennial examination.
 2. Bot. A plant which exists or lasts for two years.
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 biennial
      adj 1: occurring every second year; "they met at biennial
             conventions" [syn: biyearly]
      2: having a life cycle lasting two seasons; "a biennial life
         cycle"; "parsnips and carrots are biennial plants often
         grown as annuals" [syn: two-year] [ant: perennial, annual]
      n : a plant having a life cycle that normally takes two seasons
          from germination to death to complete; flowering
          biennials usually bloom and fruit in the second season