JENKINS, PHILIP D. Herbarium, 113 Shantz, University of Arizona, Tucson, AZ 85721. - Systematics of Browallia Linnaeus (Solanaceae, Cestroideae), inferences from morphological data.
Browallia Linnaeus (Solanaceae, Cestroideae) is native to the New
World tropics and subtropics. Taxonomists first grouped Browallia and
morphologically similar genera within the Salpiglossideae, which were
considered advanced in Solanaceae because of their derived characters.
Recent evidence indicates that Salpiglossideae is paraphyletic within
the subfamily Cestroideae and perhaps Cestroideae is primitive in
Solanaceae, and that Browallia seems more closely allied with the
large, widespread genus Cestrum. Morphological evidence, analyzed
phylogenetically and using multivariate techniques, implies that there
are five species of Browallia. The generic boundaries of Browallia
and the monotypic sister group Streptosolen jamesonii (Bentham) Miers
are doubtful. Streptosolen, erected out of Browallia in 1850, is
here resubmerged. The species recognized are Browallia acutiloba
Segástegui & Díos, B. americana Linnaeus, B. eludens R. K. Van
Devender & P. Jenkins, B. jamesonii Bentham, and B. speciosa Hooker.
Four Browallia have limited distributions: three in the South
American Andes and one disjunct in southwestern North America. The
fifth, Browallia americana, is widespread and introduced throughout
the tropics of the New and Old Worlds. It exhibits variable
characters in the Andes of Peru, but less so elsewhere, especially
where it is likely introduced. Morphological evidence suggests that
the origin of the group is Andean, and that the genus is diverging,
but that diversification does not warrant recognition of all the
species previously described. Browallia eludens, with its disjunct
range, poses interesting questions about the biogeographical history
of the group. It has a more northern range where seasonally freezing
temperatures occur. It appears to be a seasonal ephemeral with larger
seeds than the tropical Browallia, that the seeds are viable for a
number of years, and that the plants may be largely autogamous.
Key words: Browallia, phylogenetics, Solanaceae