The preparation of treatments of Dilleniaceae for the Flora of Colombia and Flora of Ecuador projects required a literature survey, visits to herbaria, and the analysis of types and general collections found on the Internet. The results indicate the need to lectotypify several species of Dilleniaceae described by the Colombian botanist José Jerónimo Triana. These taxa are based on specimens collected during Triana's participation in the Colombian Chorographic Commission (“Comisión Corográfica”) from 1851 to 1857, under the supervision of Agustín [Giovanni Battista Agostino] Codazzi. Lectotypes for the following six species are proposed herein: Davilla densiflora, Ricaurtea congestiflora, Ricaurtea nitida, Tetracera castaneifolia, Tetracera hydrophila, and Tetracera sessiliflora.

An additional fifty new species of Stelis (Orchidaceae) from Colombia are described and illustrated in this the fourth of a series that includes those not identified when compared with any of the previously known species.

Based on morphological characters and recent molecular evidence, Capparidastrum subgenus Pachycarpum (Capparaceae) is raised to generic status. As Pachycarpus is a previous and valid generic name of Apocynaceae (Asclepiadoideae), Neocapparis is here proposed as a new generic name for Capparidastrum subgenus Pachycarpum. Two new combinations for species previously placed in Capparidastrum are presented here: Neocapparis pachaca and Neocapparis quina. The new genus is restricted to Neotropical dry forests, ranging from Mexico to northern Colombia and Venezuela and disjunct to western Ecuador and Peru. Illustrations of species and full citation of collections are provided.

Dicliptera francodavilae a new species of Acanthaceae from the remnant deciduous coastal dry forests, mainly from the area of Guayaquil, in the province of Guayas, western Ecuador, is here described and illustrated. It is distinguished from the 10 remaining species of the genus in Ecuador by having an inflorescence of terminal, rather loose racemes of umbels, cymule bracteoles narrowly elliptic-oblanceolate and pilose without and lilac to purple corollas, 15–25 mm long. Dicliptera francodavilae is assessed as Vulnerable (VU B1a, b, iii).

Nine new combinations in Euploca (Heliotropiaceae) from Mexico and Central America are proposed in this paper: Euploca calcicola, Euploca cremnogena, Euploca fallax, Euploca foliosissima, Euploca karwinskyi, Euploca limbata, Euploca michoacana, Euploca queretaroana, and Euploca sessei.

A new species of Rubiaceae from South Central Vietnam is described and illustrated. The new species, Mussaenda reflexisepala, is similar to M. caudatiloba in young plant parts densely white villose, but different in calyx lobes recurved, obviously reflexed, corolla lobes yelllow to orange or reddish orange, ovate to broadly obovate, which are clearly distinguished from other known species of Mussaenda. The pollen morphology of Mussaenda reflexisepala is also reported.

A new species of Zygostates from Cochabamba, Bolivia, is described and illustrated. It is similar to Zygostates apiculata (Lindl.) Toscano, but differs by the distinctly callose sepals, petals, and labellum.

Recent systematic treatments for Jamaica have shown that the island is home to seven endemic genera of seed-plants [viz., Dendrocousinsia (Euphorbiaceae), Jacmaia (Asteraceae), Odontocline (Asteraceae), Portlandia (Rubiaceae), Salpixantha (Acanthaceae), Tetrasiphon (Celastraceae), and Zemisia (Asteraceae)]. These taxa account for over 23 species, with three genera (Jacmaia, Tetrasiphon, and Zemisia) being monotypic. Further study of these taxa revealed that five names need typification: (1) Tetrasiphon jamaicensis Urb.; (2) Senecio fadyenii Griseb.; (3) S. fadyenii var. dolichanthus Krug & Urb.; (4) S. hollickii Britton ex Greenm. [all the three Senecio taxa included in Odontocline]; and (5) Gymnanthes elliptica Sw. Lectotypes for these names are designated here. Furthermore, G. elliptica is transferred to Dendrocousinsia and the new combination is made here: D. elliptica (Sw.) Commock & K. Wurdack.

The new combinations Arabis adpressipilis, Hilliella rupidcola subsp. shuangpaiensis, H. sinuata subsp. qianwuensis, and Neuontobotrys amplexicaulis are proposed. The distinguishing characters of A. adpressipilis from A. pycnocarpa are discussed and evaluated. The new combinations in Hilliella were previously recognized in Yinshania when the genera were united but now recognized in different tribes. The basionym of the long-neglected Hesperis amplexicaulis predates that of Sisymbrium grayanum, and therefore becomes the basis for the new combination in Neuontobotrys. Sisymbrium amplexicaule and S. amplexicaule var. tenuicaule are lectotypified.

The parentage of Catasetum ×dunsterville, a natural hybrid or nothospecies, formally proposed in 1989 from the vicinity of Puerto Ayacucho, Amazonas state, Venezuela, was confirmed via artificial hybridization. The originally proposed putative parents were Catasetum pileatum and C. discolor. In nature, both species are pollinated by the same male Euglossine bees, Eulaema meriana and E. cingulata, and the two orchids are found in close proximity and have overlapping flowering seasons: the hybrid is relatively common. The artificial hybrid took 44 months (January 2014–September 2017) from the time seeds were planted to the first flowering.

Two little-known species of Meconopsis (Papaveraceae), M. lepida and M. psilonomma, first collected by Reginald Farrer on Gansu Min Shan, China, in 1914, were recently rediscovered and are here revised based on literature studies, field research and an examination of specimens. Accounts of the rediscoveries and detailed revisions are accompanied by explanatory photos, maps and tables. Two new varieties of M. psilonomma, var. zhaganaensis and var. calcicola, are described.