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Genus Eremanthus in Tribe Vernonieae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

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Genus Description

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The genus Eremanthus (Less.) belongs to the tribe Eupatorieae within Asteraceae and comprises approximately 18 species (Loeuille, 2011; POWO, 2024). It is endemic to eastern and southeastern Brazil, especially in the campos and campo rupestre of the Espinhaço Range and surrounding highlands, with a few species in coastal restinga; the genus does not occur outside Brazil (Loeuille, 2011). Eremanthus erythropappus is commonly treated as the type species (Loeuille, 2011).

Morphologically, Eremanthus comprises shrubs and small trees with simple, opposite to subopposite, decurrent, entire leaves that are frequently tomentose to sericeous. Capitulescences are terminal, often corymbose or paniculate; heads are homogamous and discoid, with usually five white to cream florets. Cypselae have pappus of numerous capillary bristles. Micromorphological features include pollen in the Eupatorieae “pollen type B” (Keeley & Turner, 1990) and short tector structures on the achene testa (Loeuille, 2011). These traits together distinguish Eremanthus from related genera within the “Pollen Group B” clade (Loeuille et al., 2015; Loeuille, 2011).

Species richness is concentrated in Minas Gerais and Bahia, with many narrow endemics in campo rupestre above 800–1,800 m. Centers of diversity lie in the southern Espinhaço and the Chapada Diamantina (Loeuille, 2011). Habitats include quartzitic and rocky campo rupestre, open grasslands, and relictual forest margins; soils are typically nutrient-poor and well-drained. The genus shows classic “campo rupestre island biogeography,” with frequent local endemism driven by edaphic specialization and isolation (Loeuille, 2011).

Intrinsic biology is incompletely known. Flowering occurs in the dry season, but pollination and dispersal syndromes are not well documented. Base chromosome number x = 10 is reported for some related Eupatorieae, and counts in the E. erythropappus complex support this (Keeley & Turner, 1990), though a comprehensive review of chromosome numbers across Eremanthus remains a gap.

Taxonomically, Eremanthus has been treated in a broad sense by Loeuille (2011), who recognized monophyletic groups of species with morphological coherence and provided nomenclatural updates. Earlier, Gardner (1849) segregated some taxa under Piptolepis; however, Loeuille (2011) included these within Eremanthus based on phylogenetic signals. The genus forms part of the “Pollen Group B” clade resolved in Eupatorieae phylogenies (Loeuille et al., 2015; Keeley & Turner, 1990), and at least some lineages within Eremanthus show ITS congruence with morphological limits. Uncertainty persists around species boundaries in the E. erythropappus–E. argenteus–E. incanus complex, where additional phylogenomic and population-level data are needed to stabilize taxonomy.

Humans value the wood of “candeia” (E. erythropappus) for turnery and specialty items, and E. glomerulatus and others are occasionally cultivated as ornamentals, though most species are obscure in horticulture (Loeuille, 2011).

Many species occur in fragmented habitats, and threats include habitat conversion, invasive grasses, and mining; conservation relies on protected areas in the Espinhaço Range (Loeuille, 2011). Continued field surveys and integrative systematic work will be essential to clarify species limits and guide conservation actions.

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