Data from: A revision of Sesuvium (Aizoaceae, Sesuvioideae)

Sesuvium and Cypselea are closely related succulent genera within the
Sesuvioideae (Aizoaceae). Since Cypselea is nested in Sesuvium in
molecular studies and both genera share traits separating them from other
members of the subfamily, we propose to include Cypselea in Sesuvium.
Sesuvium (incl. Cypselea) comprises 14 species and is distributed
worldwide with centres of diversity in southern Africa and North and
Central America. Sesuvium comprises erect to procumbent herbs with
opposite leaves that often bear conspicuous sheath-like lateral appendages
on the petioles (pseudostipules). These and the many-seeded capsules are
diagnostic traits, separating Sesuvium from the closely related genera
Trianthema and Zaleya. Sesuvium is usually found in coastal or otherwise
saline areas and is phylogenetically divided into an African (5 spp.) and
an American lineage (9 spp.). While all African species are C4 plants, the
American lineage also comprises a derived C3 lineage, which includes the
cosmopolitan species S. portulacastrum. Some floras provide descriptions
and keys for locally relevant species, but currently no comprehensive
taxonomic treatment is available for Sesuvium. In this paper, a key and
descriptions for all species are provided. Furthermore, we compile
information on the rare and poorly known species of the genus and address
issues concerning species concepts in Sesuvium, which impede species
identification. The inclusion of Cypselea in Sesuvium leads to three new
combinations: Sesuvium humifusum , Sesuvium mezianum and Sesuvium
rubriflorum .