Genomic DNA extracted from species of Cactaceae is often contaminated with significant amounts of mucilage and pectin. Pectin is one of the main components of cellular walls, whereas mucilage is a complex polysaccharide with a ramified structure. Thus, pectin- and mucilage-free extraction of DNA is a key step for further downstream PCR-based analyses. We tested our DNA extraction method on cladode tissue (juvenile, adult, and herbaria exemplars) of 17 species of Opuntia Mill., which are characterized by a large quantity of pectin and mucilage. We developed a method for the extraction of gDNA free of inhibitory compounds common in species of Opuntia Mill., such as pectin and mucilage. Compared to previously extraction protocols, our method produced higher yields of high-quality genomic DNA.

Cycads are a group of plants in the order Cycadales, comprising ten genera, and with a worldwide distribution. Very few taxonomic revisions are available for the genera in this order, and the present one is intended to provide a revision of the current knowledge in the genus Dioon. The revision was based on bibliographic research and analysis of herbarium specimens, including live specimens found in different botanical gardens and greenhouses. Sixteen species are recognized for the genus. This study includes morphological descriptions, maps with species distribution, line drawings of diagnostic characters, and a key to the species. Detailed taxonomic notes for each species, as well as information on their distribution and habitat is provided, including the uses and common names when available. Fifteen of the total species are distributed in Mexico and one species is found in the border of Honduras and Nicaragua. Therefore, the genus is endemic to Megamexico II.

Background: Euphorbiaceae is one of the largest angiosperm families in Mexico, but our understanding of its diversity and distribution is incomplete, and most genera lack taxonomic revisions. Questions: How many genera and species of Euphorbiaceae occur in Mexico, and which of these are endemic to the county or a particular state? Where is the greatest diversity? Study site and years of study: Mexico, 1990s-present. Methods: Pertinent Euphorbiaceae literature was reviewed, and major herbaria were consulted, as too was the iNaturalist platform. This information was supplemented by fieldwork. Results: Euphorbiaceae is the fifth most diverse family in Mexico, where 32 genera and 713 species occur natively. Eleven species and two genera (Ricinus y Mercurialis) are naturalized. Four genera contain almost 75 % of the species (Euphorbia, 245 spp., Croton, 130 spp., Acalypha 109 spp., and Jatropha 50 spp.), whereas 24 genera contain fewer than 10 species. Enriquebeltrania is the only endemic genus, but 413 (57 %) species are endemic. The family is distributed from sea level to 3,600 m and is found in nearly all types of vegetation. The states with the greatest diversity are Oaxaca (247 spp.), Jalisco (210 spp.), Chiapas (196) and Veracruz (189 spp.). Conclusions: Our taxonomic and floristic understanding of the family is incomplete, and few genera have a modern revision or monograph. Twelve species are included in the NOM-059-(SEMARNAT 2010), and an additional 77 are at risk following the criteria of the IUCN Red List. It is imperative to conduct more research on taxonomy, distribution, and conservation.