The nomenclature and typification of the species of Ericaceae in Singapore are discussed. A neotype is designated for Leucopogon malayanus Jack. Lectotypes are designated for Rhododendron longiflorum Lindl., R. javanicum (Blume) Benn. var. tubiflorum Hook.f., Vaccinium bracteatum Thunb. and, in a second step, V. malaccense Wight.

In the New Guinea region, including the Solomon Islands and Halmahera, three species of the pantropical genus Xylopia L. have been previously recognised: X. calosericea Diels, X. papuana Diels, and X. peekelii Diels. In recent floristic tabulations the genus has thus comprised a minor component of the Annonaceae flora. Here we present descriptions and illustrations of 14 new species of the genus from the region: Xylopia aenea D.M.Johnson & N.A.Murray, X. ampla D.M.Johnson & N.A.Murray, X. brunneola D.M.Johnson & N.A.Murray, X. bullata D.M.Johnson & N.A.Murray, X. chlorosperma D.M.Johnson & N.A.Murray, X. cornuta D.M.Johnson & N.A.Murray, X. corrugata D.M.Johnson & N.A.Murray, X. makiraensis D.M.Johnson & N.A.Murray, X. musella D.M.Johnson & N.A.Murray, X. pachysericea D.M.Johnson & N.A.Murray, X. rogstadii D.M.Johnson & N.A.Murray, X. sulangwane D.M.Johnson & N.A.Murray, X. takeuchii D.M.Johnson & N.A.Murray, and X. vulcanicola D.M.Johnson & N.A.Murray. We distinguish the 17 species in a diagnostic key. The region includes Xylopia species that are among the tallest in this genus of c. 220 species, one with the largest leaves and another with the largest fruit, as well as several species with distinctive cataphyll-covered resting buds. The genus has undergone multiple dispersals both to and within the region, with higher diversity on smaller islands than on New Guinea. Its presence on oceanic islands indicates over-water dispersal.

The tree species Morinda bracteata Roxb. is here confirmed for New Guinea after having been previously overlooked. A brief summary of its taxonomic history is given, along with its revised distribution which now appears restricted to the east of Huxley’s Line when Palawan is included.

The genus Codonoboea Ridl. (Gesneriaceae: Didymocarpoideae: Trichosporeae: Didymocarpinae) is revised for Thailand. Thirteen species are recognised, one of which, Codonoboea poopathii D.J.Middleton, is new to science and three of which, C. dawnii (Kiew) Kiew, C. oreophila Kiew ex C.L.Lim and C. urticoides (A.Weber) Kiew, are new records for Thailand. Didymocarpus reptans Jack is neotypified; D. hispidus Ridl. var. selangorensis Ridl., D. inaequalis Ridl., D. rugosus Ridl. and D. urticifolius Ridl. are lectotypified; and D. hispidus Ridl. is lectotypified in a second step. A key to the species is provided and all species are described.

The new species Allocheilos villosus B.L.Burtt ex D.J.Middleton, Didymocarpus tamdaoensis D.J.Middleton, Didymocarpus dalatensis D.J.Middleton and Loxostigma vietnamensis D.J.Middleton from Vietnam are described.

The new species Paraboea babae D.J.Middleton from Shan State in Myanmar is described and illustrated.

The new species Kopsia obscura D.J.Middleton in the Apocynaceae is described.

A new combination Gynochthodes wongiana (Suratman) W.W.Seah is proposed here based on Morinda wongiana Suratman and the name Gynochthodes suratmanii K.M.Wong & Razafim. is placed in its synonymy.

We review the history of plot-based studies of forests in Singapore and their contribution to our understanding of tropical forest ecology, especially of the regenerative capabilities of forest remnants after fragmentation, land-use change, and other disturbances. With this, we describe the establishment of the Long-Term Forest Ecological Monitoring plot network that includes the continued utilisation of sets of recently established, standardised plots along with the re-establishment of a historical set of plots surveyed by a team led by Wong Yew Kwan in 1992, ensuring the plot design is harmonised across the network.

A little-studied orchid genus, Claderia Hook.f., has until now contained just one or two species, Claderia viridiflora Hook.f. and its possible synonym, C. papuana Schltr. We describe a new species from Singapore, which differs from these Claderia in having small, cream-yellow flowers that are nodding and presented in a long, unbranched terminal inflorescence, mostly with two flowers open simultaneously. We name the new species Claderia leontocampus Niissalo. Plants of the new species have been collected or recorded in Sumatra, Peninsular Malaysia and possibly Peninsular Thailand. We carried out population genetics analyses to show distinction between the new species and Claderia viridiflora. The two species occur in the same habitat in Singapore. We used phylogenetic analyses to find out the phylogenetic position of Claderia within Orchidaceae; the genus is here considered to belong to subfamily Epidendroideae Kostel., tribe Epidendreae Lindl., subtribe Claderiinae Szlach. We publish the plastome and ITS sequences of Claderia viridiflora. Two names are lectotypified.

Three species of Vitaceae are newly recorded for Singapore. One of them, Causonis maritima (Jackes) Jackes, is treated here as native, while two of them, Cissus discolor Blume and Cissus repanda Vahl, are presumed to be introduced.

The nomenclature and typification of Pentaphragma Wall. ex G.Don (Pentaphragmataceae) and its Singapore representative are briefly reviewed. A lectotype is designated for the only generic synonym of Pentaphragma, Francfleurya A.Chev. & Gagnep. Four other lectotypifications for names of species or varieties are given, one at the second step.

The nomenclature and typification of Scaevola taccada (Gaertn.) Roxb. and its synonyms are reviewed. In total, nine new lectotypifications are presented.

Three species of Euphorbiaceae are newly recorded for Singapore, two of which (Euphorbia prostrata Aiton and Microstachys corniculata (Vahl) A.Juss. ex Griseb.) are non-native, and one (Croton erythrostachys Hook.f.) is presumed native but nationally extinct. The record of Microstachys corniculata is supposedly new for the continent. A lectotype is designated for Microstachys corniculata.

The nomenclature and typification of the species of Podocarpaceae in Singapore are discussed.

Eleven species of Iguanura are recognised for Peninsular Malaysia, one of them with two varieties. One species is described as new, Iguanura ruthiae Saw. All species are described, and notes on distribution, provisional IUCN conservation assessment and ecology are given. Thirteen taxa are synonymised and all names typified.

Field work in Panglima Sugala, Tawi-Tawi, Philippines, resulted in new country records of Begonia dimorpha S.Julia (sect. Petermannia, Begoniaceae) and Clerodendrum pygmaeum Merr. (sect. Clerodendrum, Lamiaceae), both previously recorded only from Borneo. There are now 162 species of Begonia L. and 18 species of Clerodendrum L. known from the Philippines. Field observations and taxonomic notes on each species are presented and the presence of Bornean plant elements in the Sulu archipelago is discussed.

The genus Hippeophyllum Schltr. is synonymised under Oberonia Lindl. The following names are synonymised under Oberonia scortechinii Hook.f.: Hippeophyllum alboviride J.J.Sm., H. biakense J.J.Sm., H. celebicum Schltr., H. halmaherense J.J.Sm., O. hamadryas Ridl., O. longifolia Ridl., H. micranthum Schtr., H. papillosum Schltr., H. sulense J.J.Sm. and H. wenzelii Ames. Oberonia scortechinii is an epiphyte distributed from Malaysia through Indonesia, the Philippines, to New Guinea and the Solomon Islands at elevations of 0–500 m (rarely to 1000 m).

The genus Gynochthodes Blume (Rubiaceae) in India is revised. Five species are recognised and described, including the new species Gynochthodes nilagiriensis P.Murugan, V.Ravich. & Murugan. Gynochthodes cochinchinensis (DC.) Razafim. & B.Bremer has been recorded for India but is excluded here. All names are typified.

Litsea megamalayana Karupp., V.Ravich. & Bharath (Lauraceae), a new species from the Megamalai Wildlife Sanctuary of the southern Western Ghats, is described and illustrated. A detailed description, illustration, colour photographs and a table of comparisons to an allied species are provided here for easy identification and further study.