exogen
 外長植物;雙子葉植物


 Ex·o·gen n.  Bot. A plant belonging to one of the greater part of the vegetable kingdom, and which the plants are characterized by having c wood bark, and pith, the wood forming a layer between the other two, and increasing, if at all, by the animal addition of a new layer to the outside next to the bark. The leaves are commonly netted-veined, and the number of cotyledons is two, or, very rarely, several in a whorl.  Cf. Endogen.

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 exogen
      n : flowering plant with two cotyledons; the stem grows by
          deposit on its outside [syn: dicot, dicotyledon, magnoliopsid]