Recent conservation of Sibara against the earlier-published Machaerophorus paved the way to transfer the type of the latter genus to the former. The combination S. matthioloides is proposed, and the distinguishing characters of this species from the closely related S. anethifolia are discussed.

The limits of Mostacillastrum are expanded to include 12 additional species from South America, Haiti, Mexico, and southwestern United States. A new species, M. saltaensis (Argentina) is described, and a new name, M. subauriculatum, and new combinations, M. arcuatum, M. ekmanii, M. haitiense, M. incisum, M. longipes, M. pandurifolium, M. purpusii, M. retrofractum, M. vaseyi, and M. versicolor, are proposed. A key to all 30 species of Mostacillastrum is presented.

A new species, Dracontia hydra, is illustrated and described from Costa Rica. Dracontia dracontea is characterized and illustrated, discussion is given on its taxonomical status, while Dracontia perennis is added to its synonymy.

Plinia yasuniana, a new species from Ecuadorian Amazon is described and illustrated. This new species is characterized by the large leaves with numerous, impressed lateral veins and subcordate to truncate bases. In a 25-ha plot at Yasuní National Park there are 14 individuals with dbh ≥ 1 cm.

A new species of Artemisia, A. lingyeouruennii, from western Sichuan Province, China, is described, illustrated and discussed.

The identity and taxonomic status of Masdevallia attenuata are discussed, and the species is lectotypified. Masdevallia scabrilinguis is reduced into synonymy of M. attenuata, and M. fonsecae is reconsidered and treated as a good species. Both the taxa are described and illustrated on the basis of living plants from Costa Rica.

A new species, Caryodaphnopsis parviflora, is described and illustrated. It shares with C. tomentosa small flowers with six 2-locular stamens, but differs in its glabrous leaves. Vegetatively it resembles C. fosteri closely, but the latter species has larger flowers with nine 4-locular stamens.

A survey of all known chromosome counts of gentian tribe Helieae are presented including new reports for ten species. Amongst the novelties are four genera of the Gentianaceae that are reported for the first time, Calolisianthus and Helia (both Helieae), and Schultesia and Zygostigma (both Chironieae). In the Helieae, our results reinforce the hypothesis of Weaver 1969 that two ploidy series occur in the tribe, one polyploid based on n = 20 and one dysploid based on n = 21. The basal chromosome number for the Helieae remains to be determined.

“Wolffia borealis” hitherto considered to have been validly published, was found to be not validly published and is validated here.

Rubus fockei was proposed in 1976 as a replacement name for R. fulvus, an illegitimate name published in 1910. Unfortunately, Rubus fockei had already been published in 1881, although not indexed until 1991, rendering R. fockei Gandhi illegitimate. Rubus kasthuriae is here proposed to replace R. fulvus.

We describe five new species of Miconia: M. kappellei and M. ricardoi, both endemic to the Cordillera Talamanca in Costa Rica, M. hildeana from a narrow altitudinal belt of Caribbean slope cloud forests of Costa Rica and adjacent Panama, and M. cocoensis and M. diegogomezii, both endemic to Cocos Island, Costa Rica.

The Malinalco-Tenancingo-Zumpahuacán Protected Natural Area measures roughly 150 km², within the eponymous municipalities in the State of Mexico. We undertook a comprehensive flora of the region to obtain a database with 7,187 records. The identified specimens comprise 165 families, 724 genera, and 1,704 species. The most representative families are Asteraceae with 85 genera and 191 species; Leguminosae with 51 genera and 136 species (Fabaceae 79, Mimosaceae 43 and Caesalpiniaceae 14); Poaceae with 40 genera and 89 species; and Orchidaceae with 40 genera and 90 species. We identified six distinct types of vegetation: tropical deciduous forest, tropical subdeciduous forest, montane mesophytic forest, Quercus forest, Pinus-Quercus forest, and gallery forest. In addition, we provide a list of 287 endemic species and 336 new species reports for the State of Mexico.

Herbarium and literature studies of Liparis section Ramosae (an exclusively neotropical group) reveal two new distributional records and five hitherto undescribed species whilst one other taxon requires reduction to synonymy. The new taxa are Liparis ecallosa, L. nonatra, L. schunkei, L. serratiloba and L. vargasii. Liparis lueri Dodson is proposed as a new synonym of L. serpens Garay.

Cleisostoma chrysochilum is identified as an earlier name for Trichoglottis intermedia. The former is neotypified and transferred to Trichoglottis.

A new species of Campsiandra (Caesalpinieae) from the Lower Rio Negro and Rio Amazonas of Brazilian Amazonia is described and illustrated. Campsiandra robclarkiana resembles C. nutans Stergios by the size and general characteristics of the flower and inflorescence, and C. steyermarkiana Stergios by the tortuous stamens. However, it is distinguished from all other species of the genus by the highly coriaceous nitid leaflets with appressed puberulence on both surfaces and without a waxy coating underneath.

The species of Lauraceae collected by Ludwig Riedel, excluding Ocotea, are commented and contextualized according to the different itineraries he travelled in Brazil, from 1821 to 1836, indicating the localities and dates of collections, whenever possible. To complete this work, two diaries of Riedel have been consulted and the information from them cross-checked with the annotations found on specimen labels. An annotated list of 48 entries provides information on the status of species names and their types, currently accepted names, and collections found in different herbaria. Lectotypes for five names, Aydendron verrucosum var. attenuata, Aydendron parviflorum, Mespilodaphne parviflora, Nectandra spicata, and Oreodaphne fasciculata, are designated. The species of Ocotea collected by Riedel will be treated in part II of this series.