There are actually a few different eucalypti known as silver dollar gum. The most familiar and largest is Eucalyptus polyanthemos. Mature trees that were popularly planted through the 1960s are about forty or fifty feet tall. Some stay smaller. A few that compete with taller trees are more than sixty feet tall. Trunks and limbs are somewhat sculptural, with fibrous bark.
Grayish foliage on limber stems forms a billowy and rounded canopy that blows softly in the breeze. Juvenile leaves are nearly circular, and more silvery gray than adult foliage is, like silver dollars. Ovate adult leaves are about three inches long and half as wide. Tiny flowers with prominent white stamens bloom amongst the adult foliage in spring and summer.
Smaller trees are often pruned aggressively or pollarded so that they continually produce the more desirable juvenile foliage without bloom. The problem with this technique is that it must be repeated every few years or even annually. Otherwise, vigorous secondary growth can get too heavy and break away.