The lichenological history of Saint Lucia is reviewed from published literature and catalogues of herbarium specimens. 238 lichens and 2 lichenicolous fungi are reported. Of these 145 species are known only from single localities in Saint Lucia. Important herbarium collections were made by Alexander Evans, Henry and Frederick Imshaug, Dag Øvstedal, Emmanuël Sérusiaux and the authors. Soufrière is the most surveyed botanical district for lichens.

Chaunanthus gracielae is transferred to Mostacillastrum based on a critical evaluation of morphology. The two genera are readily distinguished by habit, indumentum, leaf, flower, and fruit features. As a result, the New World Mostacillastrum now includes 31 species, of which M. gracielae is easily distinguished from the remaining species by its stigmas prominently 2-lobed opposite the fruit replum.

The controversial limits of Thlaspi are discussed, and all of its segregates proposed or revised during the past four decades are critically evaluated. As a result, the majority of specific and infraspecific names previously assigned to Thlaspi are currently placed in Noccaea, a genus the limits of which are expanded to include almost all of Thlaspi segregates. A detailed description of Noccaea, a synoptic account of its species, along with full bibliography and typification, and key to all 128 species are presented. The new names N. germanii, N. iranica, and N. meyeri and the following 36 new combinations are proposed: N. abchasica, N. antitaurica, N. atlantica, N. bornmuelleri; N. bovis, N. bulbosa, N. campylophylla, N. cappadocica, N. capricornuta, N. cilicica, N. cornuticarpa, N. crassiuscula, N. dolichocarpa, N. eigii, N. elegans, N. huber-morathii, N. jaubertii, N. kurdica, N. lilacina, N. maassoumii, N. natolica, N. orbiculata, N. oxyceras, N. perfoliata, N. platycarpa, N. pulvinata, N. rechingeri, N. rostrata, N. rosularis, N. stenocarpa, N. szowitsiana, N. triangularis, N. umbellata, N. vesicaria, N. vesicaria subsp. boissieri, and N. zangezurica. The genus Coluteocarpus is reduced to synonymy of Noccaea. Brossardia papyracea var. kotschyi, Coluteocarpus reticulatus var. boissieri, Hutschinsia trinervia, Iberidella andersonii, Thlaspi affine, T. japonicum, T. kovatsii, T. szowitsianum, and Vesicaria reticulata are lectotypified.

The Malcolmia s.l. complex was so broadly delimited that it included at least five genera in four tribes. As delimited herein, it includes Malcolmia s.str. (12 taxa, 6 spp.) of the tribe Malcolmieae, Maresia (5 spp.) and the new genus Marcus-Kochia (4 spp.) of the tribe Anastaticeae, Strigosella (23 spp.) of the tribe Euclidieae, and Zuvanda (3 spp.) of the tribe Conringieae. The new combinations M.-K. arenaria, M.-K. littorea, M.-K. ramosissima, and M.-K. triloba are proposed. Detailed generic descriptions, key to genera and their species, and data on type collections of all recognized taxa are provided. Second-step lectotypes are designated keys for Strigosella hispida, S. scorpioides, and Zuvanda meyeri. All taxa previously placed in Malcolmia are listed, and their current tribal, generic, and species assignments are given.

Three new combinations and two new synonyms of Gomesa and Trichocentrum from Brazil are proposed. The nothogenus × Ornithocidium is synonimized under Gomesa, and its natural hybrid are also combined.

An account is presented of Eria section Cylindrolobus in the Malesian part of its distribution, wherein 57 species are enumerated. Eria jenseniana is newly recorded for Peninsular Malaysia; E. wenzelii is reinstated; E. rigida var. papuana is raised to specific rank as E. pseudorigida; Ceratostylis beccariana, Cylindrolobus elatus, C. kalabakanensis, C. longpasiensis, Dendrobium korinchense and Trichotosia microbambusa are tranferred to Eria; Trichotosia subgenus Eremochlaina is lectotypified; and five new species are proposed, viz. Eria burleyi, E. clemensorum, E. gretcheniae, E. puakensis and E. warnementiae.

Studies of the Neotropical orchid genus Crossoglossa reveal seven new species and a new synonym. Discussion is also provided on some prior misidentifications, and some emended descriptions are provided to clarify the characters of previously published taxa. The novel taxa are C. boekeana, C. dressleri, C. kolanowskae, C. oliveirae, C. pellucida, C. sprucei, and C. tetraphylla. Crossoglossa dodsonii is considered a synonym of C. dalstroemii.

Two new species of Sobralia from Costa Rica are described and illustrated, and their affinities are discussed. Sobralia danjanzenii is compared to S. virginalis, from which it is mainly distinct by the simple stems and the unscented flowers, with the lip blotched with yellow only within the throat. Sobralia zebrina is similar to S. macrohylla, but it has much longer stems, ovate leaves that are matte on the adaxial side, and the lip is white with pale stripes alternating with brownish yellow stripes in throat.

In three dissertations entitled Plantarum Brasiliensium and presided by Carl Peter Thunberg, ten new species were treated in each of three parts by Johan Immanuel Billberg, Carl Gustav Ahlberg, and Carl Otto Holm, respectively, from collections made by Georg Wilhelm Freyreiss in his travel to Minas Gerais in 1814–1815. Eight of these species are currently accepted, but several have been overlooked by authors or remained unresolved until the present. Here we present the taxonomic status for all these names based on the analyses of the original specimens collected by Freyreiss, currently housed at UPS and elsewhere, pertinent literature available, and other herbarium collections. As a result, six new synonyms, one lectotypification and one new combination are proposed.

In volume IV of Herbarium Pedemontanum, Luigi Colla cited 27 species based on Brazilian specimens distributed by Carl Martius in 1827. Of them, 22 were treated as new species. The original material examined by Colla (now held at TO) was found and compared with duplicates held elsewhere. Material was located for all but six of the taxa described by Colla. Fifteen hitherto unresolved species names are here clarified, along with fourteen new synonymies, and twelve proposed lectotypifications. Based on the collecting localities and comparison with specimens at Herbarium Martii at BR and elsewhere, at least 17 of the specimens distributed by Martius could be attributed to Prince Maximilian zu Wied.

In volume V of Herbarium Pedemontanum, Luigi Colla cited 21 species based on Brazilian specimens distributed by Carl Martius in 1827. Of them, 18 were treated as new species. The original material examined by Colla (now held at TO) was found and compared with duplicates held elsewhere. Material was located for all but two of the taxa described by Colla. Fourteen hitherto unresolved species names are here clarified, and seventeen new synonymies, eighteen lectotypifications, one neotypification, and one new combination are proposed. Based on the collecting localities and comparison with specimens at Herbarium Martii at BR and elsewhere, at least sixteen of the specimens distributed by Martius could be attributed to Prince Maximilian zu Wied.