Somatic chromosomes of Stangeria eriopus (Stangeriaceae, Cycadales) were investigated by fluorescent in situ hybridization (FISH) using an 18S ribosomal DNA (rDNA) probe. Stangeria eriopus showed a chromosome number of 2n = 16 with a karyotype of 12 median-, 2 subterminal-, and 2 terminal-centromeric chromosomes. FISH study of S. eriopus revealed 16 signals made up of rDNA sites located on the terminal regions of the long arms of the 7 median- and 2 subterminal-centromeric chromosomes, on terminal region of the short arm of the 1 median-centromeric chromosome, on the terminal regions of the long and the short arms of 1 median- and 2 terminal-centromeric chromosomes. This result suggests that, not only karyomorphologically but also molecular-cytologically, the genus Stangeria may be more closely related to the genus Ceratozamia than the genus Bowenia or the genus Microcycas previously hypothesized.

Castilleja holmgrenii is described from several collections made in the Sierra Madre Occidental in southeast Sinaloa and adjacent southwest Durango, Mexico. The new species is a member of subgenus and section Castilleja. This apparently rare species is presently known from two small, geographically restricted populations. Also provided are a list of the Castilleja species of this region with notes on their status and distribution, a key for their identification, and nomenclatural and taxonomic notes concerning some of the species.

Korupodendron songweanum is described as the second genus of Vochysiaceae from Africa. Its classification, biogeography, conservation status, and local name and uses are discussed.

A new series, Passiflora ser. Carneae, and three new species are described in Passiflora subg. Astrophea: P. ascidia from Guyana and Venezuelan Guayana; P. balbis from Guyana, Venezuelan Guayana, and Amazonian Brazil; and P. saulensis from central French Guiana. A key to the 19 Guianan species of Passiflora subg. Astrophea is provided.

Aristolochia gorgona is described from the Atlantic watershed of Costa Rica and central and eastern Panama. It is similar to A. grandiflora Sw., with which it has been confused in the past. The extensive reported synonymy of A. grandiflora is reviewed and compared with the new entity. Some new terms are proposed for better describing floral structure in this species complex, and suggestions are made for its collection and study. Aristolochia gorgona is one of the largest-flowered plant species (in terms of perianth area) in the Neotropics.

A cladistic analysis was performed using nucleotide sequence variation in the rps16 intron and the trnL–F region (plastid DNA). Arcytophyllum belongs in a subclade of the tribe Spermacoceae (s.l.) together with the American species presently classified in the genera Hedyotis and Houstonia. This subclade is morphologically characterized by cymbiform seeds. Arcytophyllum is the sister group of all American Hedyotis and Houstonia and it is suggested that these latter would be most conveniently treated as a single genus, the correct name of which would be Houstonia. Arcytophyllum should be circumscribed such that it excludes A. serpyllaceum, which is not a member of the Arcytophyllum–Houstonia clade but more closely related to Bouvardia. The phylogeny that was reconstructed suggests that the ancestral area of the Arcytophyllum–Houstonia clade is the South American tectonic plate.

A review of the Argentinean specimens of Haplopappus Cass. has revealed two new species from Mendoza province, both of the section Haplopappus: H. boelkei, unique by its caespitose habit and long petiolate leaves, and H. mendocinus, related to H. macrocephalus (Less.) DC., H. ochagavianus Phil. and H. tiltilensis Phil.

Passiflora cordistipula, a new species of subg. Passiflora, ser. Lobatae, from the state of Amazonas, Brazil, is described and illustrated.

Two populations of Adiantum × variopinnatum were found at the La Selva Biological Field Station in Costa Rica. The plants were morphologically intermediate between their parents, showed additive isozyme banding patterns, and had aborted spores. Herbarium searches for the hybrid turned up specimens from Nicaragua, Costa Rica, Panama, Venezuela, and Colombia. These are the first reports of the hybrid outside of Trinidad.