三出脉，指的是在网状脉中有一种情况是在主脉基部两侧只产生一对侧脉，这一对侧脉明显比其他侧脉发达。
叶互生，具叶柄，薄革质或纸质，上半部边缘具牙齿，很少全缘，侧脉2或3对，低的离基三出脉。
Leaves alternate, petiolate, thinly leathery or papery, margin dentate in apical half , rarely entire, lateral veins 2 or 3 pairs, lowest triplinerved.
出露地层为震旦系、泥盆系、二叠系、三叠系以及侵入的花岗岩脉和花岗伟晶岩脉。
Emergence stratums are of Sinian, Devonian, Permian, Trias and intrusive granite dike and coarse - grained granite dike.
本区基性、超基性岩岩脉群的出露，从北向南可归纳为三个岩桨岩带。
There are three magmatic zones of clusters of basic and ultrabasic rocks from north to south in this area.
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