A new species of Magnolia from Sierra de Juárez, Oaxaca, Mexico, is described and illustrated. Magnolia yajlachhi belongs to sect. Talauma, subsect. Talauma, locally known as “yajlachhi” (flower of the heart, in Zapotec). It shares with M. lacandonica the subglobose mature fruit and the entirely white petals, but differs from the latter in having fewer carpels and stamens; more lateral leaf veins per side; and seeds orange vs. scarlet-red. It shares with M. zoquepopolucae the subglobose fruit but differs from the latter in having fewer carpels and stamens; petals entirely white vs. purplish in the upper portion (¾); more lateral leaf-veins per side; and seeds orange vs. scarlet-red. It shares with M. mexicana a similar number of carpels and stamens but it differs from the latter in having subglobose fruits to widely ovoid-depressed vs. widely ellipsoid; more leaf-veins per side; petals entirely white vs. adaxially purplish in the upper portion (¾); and seeds orange vs. scarlet-red. A key to Mexican species of sect. Talauma subsect. Talauma is provided. This species was assessed as Critically Endangered (CR). The species has a ceremonial and medicinal, conservation and nurse tree relevance in the Zapotecan culture.

Gradient analysis was used to determine factors driving small-scale variation of cloud forest communities harboring Magnolia dealbata, a threatened species and bioculturally relevant tree for the Chinantecan, Mazatecan, Nahuan, and Zapotecan ethnicities in southern Mexico. Particularly, we aimed to: (a) determine factors explaining major community gradients at different heterogeneity scales along a small-scale elevational gradient, (b) test the Decreasing and the Continuum hypotheses along elevation, and (c) classify vegetation to assist in identifying conservation priorities. We used a stratified random sampling scheme for 21 woody stands along a small-scale (352 m) elevational transect. Four main data matrices were used (presence-absence, density, basal area, and guild data). Through Non-metric Multidimensional Scaling (NMS), Principal Coordinates Analysis (PCoA), and distance-based Redundancy Analysis (db-RDA), we found that major community variation was explained by soil pH, displaying an outstanding vegetation discontinuity, separating the species-rich relic Oreomunnea-Ticodendron-stands from stands with higher importance values for M. dealbata. The high species richness observed was explained by a combination of the windward effect of dry-seasonal maximum cloud condensation gain and habitat differentiation-specialization, a phenomenon that may also explain the mid-peak hypothesis and ensure the survival of relic species. Sampling-truncation and conservation status also played a role in this. Our results do not support the Decreasing and Continuum hypotheses along elevation.

We describe and illustrate Magnolia mixteca, a new species of Magnolia sect. Macrophylla from the Alto Balsas Basin in Oaxaca, Mexico, providing information about its ecology, biogeography and conservation status. Magnolia mixteca differs from M. nuevoleonensis in having larger flowers, longer petals, a yellow petal-blotch, a tan-sand coloured ovary and more numerous stamens and carpels. In addition, we provide a distribution map and key to species of sect. Macrophylla. The relict distribution of this species allows us to consider it endangered (E).

A new species of Magnolia from the southern Sierra Madre Oriental, Mexico, is described and illustrated, providing information about its habitat distribution, ecology, biogeography and conservation status. After 12 fieldwork expeditions near the border of the states of Hidalgo and Puebla, we have developed morphological, ecological and biogeographic data to support recognition of populations from Acaxochitlán, Hidalgo and Pahuatlán, Puebla as a distinct species of Magnolia sect. Macrophylla. A key to species of this section and a distribution map for Mexican taxa are provided. The species was assessed as critically endangered (CR).