Solanum bradei
Not known
Solanum bradei is restricted to the Brazilian states of Minas Gerais, Rio de Janeiro and São Paulo. The known specimens are mainly from the Mantiqueira mountain range in the border area between those states, with one disjunct collection from Serra do Mar, in the Bocaina region of northeastern São Paulo State. Occasional in the understory or shaded forest edges of well-preserved or secondary fragments of the Brazilian Atlantic coastal rainforest (Floresta Ombrófila Densa of Veloso et al. 1991), normally close to water courses, in elevations ranging from 1, 000 to 2, 000 m. In cultivation in Belo Horizonte, Solanum bradei flowered year round. Preliminary crossing studies suggested it was self-incompatible as no fruits were produced in selfed plants, but more individuals should be used for a definitive conclusion.
Solanum bradei is a member of a small monophyletic lineage (the S. inornatum group) within the larger Brevantherum Clade (sensu Sarkinen et al. 2013).
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(IUCN, 2013). Endangered (EN) B1; B2 ab (ii, iii, iv). The EOO and AOO calculated were 4, 076.04 km2 and 48 km2respectively resulting in the assessment of the Endangered category. The species is known from eight localities only, most of which are subject to urban expansion and deforestation due to tourism and agriculture. Although the species is known to occur in three protected areas [Área de Preservação Ambiental Serra da Mantiqueira (APA Mantiqueira), Parque Estadual de Campos do Jordão and Parque Nacional de Itatiaia] we suggest to maintain it as Endangered due to: the effectiveness of APAs in protecting the species is doubtful, the Parque Estadual de Campos do Jordão have considerable areas with exotic species, and both it and Parque Nacional do Itatiaia have considerable areas with habitats not suitable to Solanum bradei (such as outcrops and highland grassfields). Although Solanum bradei is known to grow on secondary fragments and in a wide elevation range, threats to it are clear, considering that the southern Mantiqueira range, where most collections are from, is situated between the two main urban centers in Brazil and has become a tourism hub. In addition, over the past few decades the montane forests and the highland fields of Mantiqueira have been increasingly converted to pastures, monocultures or urban centers.
Solanum bradei is the most widely distributed and morphologically variable species of the Solanum inornatum species group. It is the only species of the group not necessarily associated with well-preserved sites, although always found in shaded environments, and is also the one that has the broadest elevational range. Despite the usual shrubby, robust habit of the species, specimens as small as 20–25 cm tall were found flowering, these mainly from the municipalities of Camanducaia and Gonçalves, in southern Minas Gerais State. The species has distinctive geminate sympodia, with leaves differing in shape and size to a degree not observed in any other species of the group. Although this character was observed in all specimens in the field, some branches preserved on herbarium sheets do not retain well-developed minor leaves. Due to this, anisophylly was not used as a diagnostic character to separate the species, but it is certainly a useful character in the field.
Some plants seem to develop diseased flowers, possibly the result of fungal or viral infection, as has been previously reported in other species of Solanum (see Hernández and Hennen 2003). In these cases an unusual form of calyx growth is observed where the expanded calyx covers the entire flower, making it resemble a fruit. This has resulted in misleading annotations on some labels [e.g. Polisel et al. 228 (SPSF) has “Fruto imaturo verde” written on the label but the specimen is actually flowering]. When dissected, the diseased flowers show an opened and lobed corolla, retained in the expanded calyx, and purplish blue anthers (in dried material) that produce less pollen than normal. These putatively infertile flowers are more common in young plants from disturbed areas.
Solanum bradei can be easily distinguished from Solanum inornatum by its tiny deltate calyx lobes (1–2 mm long) that are not accrescent in fruit and its long-pedunculate inflorescence (peduncles up to 1 cm). Solanum inornatum has linear, 3–5 mm long calyx lobes and inflorescences with peduncles 1–4 mm long. The characters that separate it from the other species described in this paper are discussed further below, on each species discussion.
In the past, sheets of Solanum bradei have been determined as Solanum apiahyense Witasek by various Solanum taxonomists, another poorly known species of uncertain affinities from secondary formations in São Paulo, Paraná and Santa Catarina states. More recently, Solanum apiahyense was found to be closely related to Solanum trachytrichium Bitter, a species previously assigned to the Geminata clade (Knapp 2002b, L.L. Giacomin in prep.). Among species that could be confused with members of Solanum inornatum group and that are not considered part of the Brevantherum clade, these two (Solanum apiahyense and Solanum trachytrichium) are the only ones that we judge should be mentioned here. They can be distinguished from all species of the Solanum inornatum group by having inflorescences with fruiting peduncle longer than 1 cm and pedicels apically expanded with a constriction at the receptacle. The pubescence of the species are also distinctive: while Solanum apiahyense has very long, multicellular (up to 7 cells) unbranched trichomes, Solanum trachytrichium has unicellular trichomes that are hooked on a mound-like base, giving the leaves an scabrous aspect, rough to the touch (Knapp 2002b).
The epithet honors the German botanist Alexander C. Brade [1881–1971] who greatly contributed to the growth of botany in Brazil in the middle 1900s. His efforts to better understand the flora of Itatiaia led to the earliest known collections of Solanum bradei.