The predominantly Australasian genus Patersonia R. Br. (Iridaceae, Patersonioideae) includes 18 species in Australia, one in New Caledonia, and just one currently recognized species in the Malesian archipelago, although two more have been described previously but are now reduced to synonymy. After examining the available collections of the genus from this vast area, I have identified two distinct sets of populations in Borneo, two more in New Guinea, one in Sumatra, and one in Mindoro, The Philippines. Many collections lack flowers or are poorly preserved, yet greater-than-expected differences in vegetative and some fruit features for a single species are evident among the six population sets. Morphological variation includes leaf size; marginal vestiture and microscopic surface structure; flowering stem orientation, width, and length relative to leaves; inflorescence spathe and floral bract vestiture; and absence or presence and type and amount of pubescence on perianth tube and ovary. Recognition of just one hypervariable Malesian species does not adequately reflect the biological situation. I propose the following: recognition of P. borneensis Stapf and the west New Guinean P. novo-guineensis Gibbs, currently subsumed in P. lowii Stapf; addition of a second species in Papua New Guinea, P. inflexa Goldblatt; and treatment of the Sumatran highland plants as P. sumatrensis Goldblatt from Indonesia. Philippine plants from Mindoro match none of these and represent another species, P. philippinensis Goldblatt. Lectotypes are designated for the two names P. lowii and P. novo-guineensis. This taxonomy awaits provenance of flowers with well-preserved perianths of all but P. lowii and P. borneensis and capsules and seeds of P. philippinensis, but are unlikely to alter this treatment. Floral differences among most Patersonia species are small, except for the vestiture on tepals and tube visible in many of the available specimens, and for the most part involve only modest differences in size and color of the tepals.

Concepts about development of the plant component of New World terrestrial ecosystems through deep time have reached a point where it is possible to consider some subtle and refining details about the process. One such detail is the temporal relationship between the opportunity of new habitats provided by the physical processes of landscape development and long-term climate change, and the availability of the mostly angiosperm lineages that presently occupy these habitats. Some habitats (e.g., beach/strand/dune) were in existence long before the rise of the flowering plants ca. 125 million years ago (Ma), and some did not develop until late in the Neogene from a combination of cooling climates and locally to regionally increasing elevations (alpine tundra/páramo). In other instances, both habitats and lineages existed contemporaneously, but in different parts of the world, so development of the particular ecosystem had to await the appearance and spread in the New World of the lineage through migration (e.g., Rhizophora L. into modern mangrove habitats after the Late Eocene; Quercus L. from the north into modern oak–Weinmannia L. habitats only after 330 thousand years ago (Kyr). The temporal correspondence between opportunity and availability joins the more widely recognized forcing mechanisms of geologic and climate change, acting on evolutionary processes, as one additional factor in better understanding the origin, composition, and distribution of the ecosystems that presently characterize the New World.

The genus Peristethium Tiegh. (Loranthaceae) is re-established to comprise five species previously placed in Struthanthus Mart. (P. aequatoris (Kuijt) Kuijt, P. leptostachyum (Kunth) Tiegh., P. lojae (Kuijt) Kuijt, P. polystachyum (Ruiz & Pav.) Kuijt, and the new nomenclatural combination presented here, P. tortistylum (Kuijt) Kuijt). Also included are five species from Cladocolea Tiegh. (P. archeri (A. C. Sm.) Kuijt, P. peruviense (Kuijt) Kuijt, and P. primarium (Kuijt) Kuijt), with two transferred as new nomenclatural combinations herein, P. nitidum (Kuijt) Kuijt and P. roraimense (Steyerm.) Kuijt). Additionally, five new species are described and illustrated (P. attenuatum Kuijt, P. colombianum Kuijt, P. confertiflorum Kuijt, P. lamprophyllum Kuijt, and P. palandense Kuijt). The genus Peristethium thus consists of 15 species and a key is provided for the genus. It is characterized by pairs of conspicuous, often caducous, chaffy scale leaves at the base of the mostly determinate inflorescences, and by lateral inflorescence units that are triads and/or ebracteolate single flowers called monads (in one case, partly pentads). Some species have bisexual flowers while others are dioecious; flowers are either tetramerous or hexamerous, and one pentamerous species is included (P. nitidum). The minute anthers are sessile or nearly so, placed far above the middle of the petals. Geographically, the genus reaches from northern Bolivia to Costa Rica, with two rare, narrow endemics on Mt. Roraima in Venezuela and the Pakaraima Mountains.

A taxonomic revision of the genus Phyla Lour. is provided. Phyla is a small genus in Verbenaceae, placed in the tribe Lantaneae and represented by five species and three varieties. Four species are found only in the Americas, and one, P. nodiflora (L.) Greene, is found worldwide in tropical and temperate areas. Detailed morphological descriptions are given for each taxon, as well as a key for their identification, illustrations, synonymy, distribution, selected specimens, and discussion about the relationships among closely related taxa. Cryptocalyx nepetifolia Benth. is lectotypified, and one new combination is proposed, P. nodiflora var. minor (Hook.) N. O'Leary & Múlgura.