Arborvitae is relatively shallow-rooted and isolated individuals are subject to windthrow and uprooting. In forest situations or when planted in dense screens or windbreaks some windfirmness may be the result of natural root grafts between adjacent trees. Because of their shallow position, the roots are easily exposed in lawns. Male and female flowers of eastern arborvitae, a monoecious species, are usually borne on separate twigs in the spring. Male flowers are yellowish and arise from branchlets near the base of shoots.
Female flowers are pinkish and appear at the tips of short terminal branchlets.
Ripe cones, which are pale cinnamon brown, mature in August to September and are up to 0.5 inch long. Similar to junipers in use and appearance, eastern arborvitae is distinguished from the junipers by their flattened branchlets. The common test is to look at the underside of the leaves. Those of Chamaecyparis show whitish marks, giving them a silvery appearance, whereas the leaves of an arborvitae are generally green on both sides. But the rule is not absolutely reliable for either species.