"Yu" and "jade" are homophonic, so they symbolize wealth. Because elm has always been known as "elm pimple", it is also known as intractable.
Elm (scientific name: elm): also known as spring elm and white elm. , commonly known as "elm pimple", is a deciduous tree of Ulmus, with smooth bark of young trees, grayish brown or light gray, dark gray bark of big trees, irregular deep longitudinal cracks and rough epidermis; Branchlets glabrous or hairy, without swollen cork layer and raised cork wings; Winter buds are nearly spherical or ovoid.
Leaves are oval, oval, etc. The leaves are smooth and hairless, the back of the leaves is pubescent when they are young, then they become hairless or some veins have tufted hairs, and the petiole surface is pubescent. The leaves of flowers bloom first and cluster in the axils of branches. Samara sparsely obovate, rounded. The flowering and fruiting period is from March to June (later in Northeast China).