(Biology)(of a plant, marine invertebrate, or structure) tree-shaped;arborescent; branching (生)(植物、海洋无脊椎动物或结构)树状的;分枝状的 ■(Palaeontology)denoting graptolites of a type that formed much-branched colonies, found chiefly in the Ordovician and Silurian periods (古生物)(主要指奥陶纪和志留纪多分枝的笔石群体)树形笔石的
noun
(Palaeontology)a graptolite of this type (古生物)树形笔石