Primers for the amplification and sequencing of DNA fragments from chloroplast genes and non-coding regions are provided to facilitate molecular phylogenetic studies aimed at building a tree-of-life for the Asteraceae. The primers reported here have been extensively tested and some empirical guidelines are included to facilitate their use.

A new genus, Andeimalva, is described to accommodate four species previously placed in Tarasa and Malacothamnus. The taxonomic placement of the Chilean species M. chilensis in the primarily North American genus has been questioned for nearly 40 years. This species occurs in the Andes of central Chile, unlike the rest of the genus, which is distributed in California, Baja California, and Mexico. Molecular phylogenetic data revealed the strongly supported relationship of Malacothamnus chilensis to the Andean species Tarasa machupicchensis, T. mandonii, and T. spiciformis. The latter species share with M. chilensis the unusual base chromosome number of x = 6, which is not found in other members of Tarasa or other closely related genera (x = 5), or the North American Malacothamnus (x = 17). Considering the phylogenetic and chromosome data, as well as morphology and geography, these four species form a clade that merits generic status and are recognized at generic rank.

Phyllanthus section Nothoclema, after revision, includes 10 species that are notable in the genus for their use as “barbascos” (fish poisons). The section is remarkable for its palynological diversity, which provides important diagnostic characters for distinguishing species. Two new species are described, both from Venezuela: P. liesneri from Falcón and Yaracuy; and P. meridensis from Mérida. Although pollen material is lacking for study, both species appear related to congeners with 3-colporate pollen having a vermiculate-reticulate exine. Phyllanthus graveolens is treated as a polytypic species, including P. micrandrus as a subspecies. Two subspecies are recognized within P. brasiliensis, the species most commonly used as a fish-poison; ssp. brasiliensis throughout most of its range includes mostly sterile semidomesticated clones.

Peperomia hobbitoides is described as a new species from karst rain forests of extreme southeastern Veracruz, Mexico. The new species grows directly on outcrops of karstic limestone, sprouting from corms lying in tiny soil pockets of ledges, depressions, and holes in the rock. It may be distinguished from all previously described species of Peperomia of Mexico and Central America by the combination of the small perennial corm, the broadly ovate acuminate-tipped leaves with cordate bases and campylodromous venation, and the ellipsoid fruit 1.5–2.0 times as long as thick with a distinct narrow apical appendage ca. 0.15–0.3 mm long. The herbage of the new species has a strong fragrance and flavor of fresh coriander (cilantro) and is eaten by inhabitants of the area. Peperomia hobbitoides is most similar morphologically to P. asarifolia Schltdl. & Cham. and P. bernoullii C. DC. but is easily distinguished from both.

Tetraneuris is recognized as a genus separate from Hymenoxys and a taxonomic treatment is presented for the 14 taxa recognized as constituting Tetraneuris: T. acaulis var. acaulis, T. acaulis var. arizonica, T. acaulis var. caespitosa, T. acaulis var. epunctata, T. argentea, T. herbacea, T. ivesiana., T. linearifolia var. linearifolia, T. linearifolia var. arenicola, T. scaposa var. scaposa, T. scaposa var. argyrocaulon, T. torreyana, T. turneri, and T. verdiensis. The revision includes synonymies, typifications, descriptions, discussions, and range maps for each of the accepted species.

A new, rare species of Ourisia from the department of La Paz in Bolivia is described based on three recent collections. The new species, Ourisia cotapatensis, is closely related to Ourisia pulchella from Bolivia and Peru and the other species of Ourisia from the central and northern Andes.

A taxonomic treatment of the genus Platanus L. in North America is presented, concentrating on the species native to Mexico and Guatemala. Eight taxa are recognized for North America: 3 species with 2 varieties each, and two species without varietal subdivision; all occur in Mexico and/or Guatemala except for one more northern variety. One previously unrecognized species from western Mexico is described, P. gentryi Nixon & Poole. Another species from northeastern Mexico, although often called P. mexicana Moric., represents an undescribed species because the name P. mexicana is correctly applied to a different Mexican species. The resultant new species is P. rzedowskii Nixon & Poole. A new variety, P. mexicana var. interior Nixon & Poole, is described from central Mexico. A key to taxa includes the two Old World species, P. kerrii and P. orientalis, but complete descriptions of the latter species are not given. A discussion of the morphological characters, biogeography, infrageneric phylogeny and speciation of Platanus in North America is presented in light of the greater understanding of the taxa afforded by this study.

Condalia sonorae is described as a new species from north central Sonora, Mexico. The taxon was previously considered part of Condalia correllii, but differs in having bicolored leaves, denser young-stem and leaf vestiture, petaloid flowers, and more spheroidal fruit endocarps. In contrast, C. correllii, has concolorous, abaxially glabrous leaves, shorter stem vestiture, apetalous flowers, and more ovoid fruit endocarps. Comparisons are also made with C. velutina, C. mexicana and C. hookeri.

Echites exilicaulis Sessé & Moç. is shown to belong in the genus Mandevilla and that it is a species distinct from Mandevilla andrieuxii (Müll. Arg.) Hemsl. Accordingly Mandevilla exilicaulis (Sessé & Moç.) J. K. Williams is proposed.

Galinsoga crozierae from the state of Durango, northwest Mexico is described and its salient morphological features compared to those of other species in the genus.