Chorological and taxonomic notes on African plants, 4: Caryophyllales.
Some taxonomically critical and poorly known taxa from the order Caryophyllales are discussed. Both molecular and morphological data suggest that the chorologically distant populations of Tribulocarpus dimorphanthus in Namibia and East Africa are not uniform. Consequently, a new combination for Tetragonia somalensis, previously described from East Africa, is made within the genus Tribulocarpus (as T. somalensis). A single record of T. dimorphanthus from South Africa is suggested here to be erroneous, so that in its new circumscription, T. dimorphanthus is endemic to Namibia. The morphology of Caroxylon nollothense and related taxa is discussed, and C. angolense and C. luederitzense are placed in the synonymy of C. nollothense. New records from southern Africa are presented for the poorly known Dysphania pseudomultiflora. Suaeda spicata, so far known only from Spain and Morocco, is recorded for Tunisia. The composition of the genus Chenopodium s.l. in its recent circumscription is revised for the flora of the Mascarenes, and C. blomianum is recorded for Mauritius. Sesuvium verrucosum from the Americas is recognized as a naturalized species on the São Vicente Island (Cape Verde). Opuntia elatior is recognized as a naturalized plant in Tunisia. A diagnostic key to the naturalized cacti in northern Africa is provided. Sagina apetala is recorded for Tanzania and the whole eastern Africa. Mollugo verticillata is recorded from South Africa for the first time. Oxygonum sinuatum, a species native to eastern and southern Africa, is recorded as a common weed in inland areas of the Santo Antão Island (Cape Verde).