Vessels solitary with angular outline ; perforation plates scalariform ; intervessel pits and vessel - ray pitting alternate to scalariform ; helical thickenings only in vessel elements tails 导管横切面为多角形，单管孔，散生。螺纹加厚仅出现导管分子尾端。梯状穿孔为主。
3.
Wood semi - ring - porous ; vessels solitary with angular outline ; perforation plates reticulate and scalariform ; intervessel pits and vessel - ray pitting alternate ; helical thickenings throughout body of vessel elements 单管孔，散生；整个导管分子上具螺纹加厚。网状和梯状穿孔。
