Two new species of Convolvulus (Convolvulaceae), C. excelsus R.R.Mill and C. infantispinosus R.R.Mill, are described from Saudi Arabia. Convolvulus excelsus, an exceptionally tall species, has affinities with C. erinaceus Ledeb. but is phytogeographically disjunct from that and other allied species. Two new subspecies are also described: Convolvulus hystrix Vahl subsp. dhofarica R.R.Mill, from Oman, and C. oxyphyllus Boiss. subsp. sheilae R.R.Mill, from Saudi Arabia. Each novelty is given a provisional IUCN conservation assessment.

The typification of Rivca ornata (Roxb.) Choisy (Convolvulaceae), based on Lettsomia ornata Roxb., is discussed. R. ornata is shown to have been frequently (though not consistently) misapplied to a taxon from S India and Sri Lanka which has also been called Convolvulus candicans Roth ex Roem. & Schult., nom. illegit.; it is here newly described as R. wightiana R.R. Mill. Lettsomia ornata was based on a specimen of a plant introduced to Calcutta Botanic Garden from Uttar Pradesh. This is synonymous with Rivea ornata var. griffithii C.B. Clarke, not Clarke's ‘typical variety’ which Prain formally named var. typica. Lectotypifications are proposed for two species names in Argyreia Lour. Calystegia hederacea Wall., Convolvulus arvensis L. and Dichondra repens J.R. & G. Forst. are recorded from Bhutan for the first time.