Pachygenium muyscarum, a new species from Colombia, is described, illustrated, and aspects related to its distribution, ecology, conservation status, and relationships with morphologically similar species are discussed. This species is characterized by flowering without leaves, labellum 1.4–1.6 cm long, with the apex trilobulate and labellum nectar glands 0.2–0.4 cm long, subulate and uncinate. To date, this is the only species of the genus present in Colombia, being endemic to the subxerophytic enclaves of Cundinamarca.

Most of the ants that are associated with plants usually nests in vegetative organs such as stems, leaves o petioles. Aiming to contribute to the plant-insect interactions, we report the first record of Crematogaster carinata nesting inside the fruits of Macropsychanthus comosus. We did fieldwork in two localities of department of Antioquia and one of the Bolivar department, we opened 32 pods and determined the insects inside them. We found Crematogaster carinata and a beetle (Coleoptera: Chrysomelidae: Bruchinae) inside. 15 of the 32 pods had ants (47 %), but only seven of them had queens (22 %). The ants left the falling pods. The beetle larvae drilled 15 seeds (14 %). This report points the importance of the research in legume-insect interactions, ant-behavior, trophic webs, and trade-off relationships research.

Mazaceae, a family native to Asia and Oceania, is reported for the first time for the Colombian flora, with Mazus pumilus (Burm.f.) Steenis. This species is easily recognized by its herbaceous habit, leaves rosulate, elliptic to obovate cauline leaves, terminal, racemose inflorescences, bilabiate flowers with one 2-lobed upper lip and one 3-lobed lower lip, and fruit completely enclosed in the calyx. To date, this species has been recorded in three departments of Colombia, growing between the pavement. Additionally, we clarify the synonyms of this taxon.

Polycarpon tetraphyllum subsp. tetraphyllum, a species mostly occuring naturally in the Mediterranean region, is recorded for the first time for the Colombian flora. This species is easily recognized by its scarious stipules, flowers with five keeled sepals with scarious margins, three white petaloid staminodes, and D-shaped papillated seeds. To the date, this species only has been recorded in Bogotá D.C., growing through the pavement. Additionally, we present the first key to genera of the Caryophyllaceae present in Colombia.

Macropsychanthus magnus a new species from Costa Rica and Nicaragua is described, illustrated, and its morphological relationships with related species are discussed. Macropsychanthus magnus is characterized by its papyraceus leaflets, with 12–15 pairs of secondary nerves, terminal or axilar inflorescences, flowers 1.8–2.4 cm long, standard 1.7–1.9 × 2.1–2.4 cm, wings 1.9–2.4 × 1.4–1.6 cm, cuspidate keels 1.7–1.9 cm long, turgid fruits with fuscous indumentum and two to four overgrown seeds. This new species is related with Macropsychanthus malacocarpus, from which it differs by its pendule flowers, wider standard, wider wings and rugose seeds. Until the date, this species is restricted to Costa Rica and Nicaragua. For these two countries, I present a key to the genera of the Dioclea clade and a key to the species of Macropsychanthus.