umbrella treeEnglishOxford New American Dictionaryumbrella tree /ˌəmˈbrelə trē, ˌəmˈbrɛlə tri/ ▸ noun either of two small trees or shrubs with leaves or leaflets arranged in umbrella-like whorls. ● (also umbrella magnolia) a North American magnolia (Magnolia tripetala, family Magnoliaceae). ● an Australian plant that is widely grown elsewhere as a houseplant (Schefflera actinophylla, family Araliaceae).