Alangium is a small genus of about 40–57 species of flowering shrubs, small trees, and one liana (A. kwangsiense), placed in the dogwood family Cornaceae (order Cornales) or sometimes segregated into the monotypic family Alangiaceae. The genus ranges across tropical and warm-temperate Asia, Africa, and the Pacific, and molecular phylogenetic work published in 2011 confirmed that Alangium is the sister group of Cornus, supporting its inclusion within a broadly circumscribed Cornaceae.
Plants in the genus share a recognisable suite of vegetative features: alternate leaves that are undivided or lobed, petiolate, without stipules, typically asymmetric, and often bearing domatia (small pit-like structures in vein axils). The inflorescences are axillary cymes. Flowers are actinomorphic and bisexual, bearing 4–10 petals and sepals and anywhere from 4 to 40 stamens; the style is two- to four-lobed and the ovary has one or occasionally two locules. The fruit is a fleshy drupe containing one or two seeds.
The genus has been divided since 1939 into four sections — Conostigma, Rhytidandra, Marlea, and Alangium — though some authors have treated Marlea and Rhytidandra as separate genera, and further revision of the infrageneric classification is expected. The type species is Alangium decapetalum, now treated as a subspecies of A. salviifolium. Several species, including A. chinense, A. platanifolium, and A. salviifolium, are cultivated as ornamentals.
Etymology
The genus name Alangium is a Latinization of alangi, the Malayalam name used in Kerala for Alangium salviifolium. The name was established in 1783 by the French botanist Jean-Baptiste Lamarck in his Encyclopédie Méthodique.
Distribution
Alangium occurs across the tropics and warm-temperate regions of Asia (including South Asia, Southeast Asia, and East Asia), Africa, and Australasia. The name's Malayalam origin reflects the genus's presence in the Indian subcontinent, where A. salviifolium is native to Kerala and neighbouring regions.
Taxonomy Notes
Depending on classification system, Alangium is either placed as a genus within a broadly defined Cornaceae (order Cornales) or treated as the sole member of a separate family Alangiaceae. A 2011 phylogenetic analysis of DNA sequences resolved Alangium as sister to Cornus, providing molecular support for the broader Cornaceae concept. Within the genus, four sections have been recognised since 1939: Conostigma, Rhytidandra, Marlea, and Alangium; Marlea and Rhytidandra have sometimes been elevated to generic rank. The type species, A. decapetalum, is now considered a subspecies of A. salviifolium.
