Tolmiea diplomenziesii, the diploid entity traditionally treated within a broadly circumscribed Tolmiea menziesii, is here formally described. Evidence is provided that this new species represents the diploid sister lineage to T. menziesii, which is re-circumscribed to include only autotetraploid plants. The diploid and autotetraploid entities are compared, and serve as an example of the level of taxonomic evidence for specific status that we consider appropriate for recognition of a cytological entity as a distinct species.

Symplocos saxatilis from Serra do Cipó, Minas Gerais State, Brazil, is newly described and illustrated on the basis of field and herbarium studies. It appears to be restricted to “campo rupestre” (rocky field) habitats. This new species is characterized by its 1- to 3-flowered pedunculate inflorescence, 11 to 14 staminodes of the pistillate flowers, and 0.7–1.5 mm thick endocarp.

Malaxis molotensis, a new orchid species from a wet cloud forest of the Sierra Madre del Sur, Guerrero, Mexico is described and illustrated. In habit and floral structure it resembles the widespread M. histionantha but differs in the elliptic labellum with incurved distal margin, and elongate, oblong-falciform pollinaria.

Listera fugongensis, a new species from Yunnan, China, is described and illustrated. The new species is probably related to Listera nipponica, but differs from it by having green flowers, petals slightly wider than lateral sepals, and a toothed lip with ciliate margins.

Phenetic analyses of morphological variation were used to elucidate distinctiveness and circumscription of taxa within the genus Froelichia in North America. Preserved specimens representing all recognized taxa and one suspected hybrid taxon were measured for 39 continuous and discrete characters and subjected to univariate and multivariate analyses. Principal coordinate analysis indicated the presence of three distinct groups of species with intergradation of morphological intermediates. Two of the groups corresponded to two large complexes of species, the F. floridana complex of the south-central and southeastern United States and the F. interrupta complex principally of Mexico, while the third consisted of F. gracilis native to the southern United States and adjoining Mexico. Discriminant analysis on each of the two complexes indicated morphologically distinct forms within each morphologically variable complex. The use of novel characters for the discrimination of taxa resulted in the identification of less plastic traits among the recognized species. Use of these newly discovered traits provides more reliable means for the identification of taxa. An instance of potential hybridization among three taxa in southern Texas was additionally explored with the putative hybrid taxa exhibiting an intermediate combination of morphological traits between each of the putative parents.

Chromosome numbers for a total of 54 individuals representing 13 genera and 40 species of Cactaceae, mostly in tribe Trichocereeae, are reported. Five additional taxa examined belong to subfamily Opuntioideae and other tribes of Cactoideae (Browningieae, Pachycereeae, Notocacteae, and Cereeae). Among Trichocereeae, counts for 35 taxa in eight genera are reported, with half of these (17 species) for the genus Haageocereus. These are the first chromosome numbers reported for 36 of the 40 taxa examined, as well as the first counts for the genus Haageocereus. Both diploid and polyploid counts were obtained. Twenty nine species were diploid with 2n =2x =22. Polyploid counts were obtained from the genera Espostoa, Cleistocactus, Haageocereus, and Weberbauerocereus; we detected one triploid (2n =3x =33), nine tetraploids (2n =4x =44), one hexaploid (2n =6x =66), and three octoploids (2n =8x =88). In two cases, different counts were recorded for different individuals of the same species (Espostoa lanata, with 2n =22, 44, and 66; and Weberbauerocereus rauhii, with 2n =44 and 88). These are the first reported polyploid counts for Haageocereus, Cleistocactus, and Espostoa. Our counts support the hypothesis that polyploidy and hybridization have played prominent roles in the evolution of Haageocereus, Weberbauerocereus, and other Trichocereeae.