A morphological phylogenetic analysis ofAesculusL. andBilliaPeyr. (Sapindaceae)

Abstract

The hippocastanaceous Sapindaceae (family Hippocastanaceae) consists of two genera: Aesculus and Billia. The genus Aesculus (buckeyes) is distributed throughout the northern hemisphere. Twelve of the thirteen species of Aesculus are found in eastern Asia and North America, and one is native to Europe. The two species of the genus Billia are found in South and Central America. Aesculus is traditionally divided into five sections. This analysis, based on morphological characters, suggests that the monotypic section Parryanae (Aesculus parryi Gray) is sister to the remainder of the genus, and the other species are divided into two clades. One clade comprises all species from southeastern North America with the monotypic section Macrothyrsus (Aesculus parviflora Walt.) as sister to section Pavia. The other clade consists of all species found in Eurasia included in sections Aesculus and Calothyrsus, with the only North American member of this clade (Aesculus californica (Spach) Nutall) as sister to the rest of the group. According to this analysis, section Calothyrsus is rendered paraphyletic by the inclusion of section Aesculus. In contrast to previous studies that suggest an Asian origin for the genus, our study suggests an American origin for Aesculus from an ancestor similar to Billia with a single migration to Eurasia via the Bering land bridge.Résumé : Les Sapindaceae hippocastanoïdes (la famille des Hippocastanaceae) sont formées de deux genres, Aesculus et Billia. Le genre Aesculus (les marronniers) est répartie dans l'ensemble de l'hémisphère nord. La majorité des 13 espèces du genre se retrouvent en Asie de l'Est et en Amérique du Nord. Une seule espèce est indigène en Europe. Les deux espèces du genre Billia sont distribuées en Amérique Centrale et du Sud. Le genre Aesculus est traditionnellement divisé en cinq sections. Cette analyse phylogénétique fondée sur des caractères morphologiques place la section Parryanae (Aesculus parryi Gray) comme groupe frère du reste du genre, ce dernier étant subdivisé en deux clades. Le premier clade inclut toutes les espèces du sud-est de l'Amérique du Nord, c'est-à-dire les sections Macrothyrsus et Pavia. La section Macrothyrsus est monotypique (Aesculus parviflora Walt.) et groupe-frère de la section Pavia. Le second clade regroupe toutes les espèces retrouvées en Eurasie (sections Aesculus et Calothyrsus). Aesculus californica (Spach) Nutall, la seule espèce américaine de ce clade, se retrouve à la base. La section Calothyrsus est rendue paraphylétique par l'inclusion de la section Aesculus. Contrairement à certaines études antérieures qui suggèrent une origine asiatique pour le genre Aesculus, notre étude propose plutôt une origine américaine à partir d'un ancêtre similaire à Billia, suivi d'une seule migration vers l'Eurasie via le détroit de Béring.

Plastid and nuclear DNA markers reveal intricate relationships at subfamilial and tribal levels in the soapberry family (Sapindaceae)

“…2) is somewhat dependant on the placement of Xanthoceras sorbifolia. Although Billia and Handeliodendron, thought to be close relative of Aesculus (Xiang et al, 1998;Forest et al, 2001), were not sampled here, the analysis confirms the definition of Hippocastanoideae as previously suggested by Judd et al (1994) and Harrington et al (2005). This temperate clade is charac- terized by deciduous opposite simple leaves (generally palmatilobate), two ovules per locule and a type-A pollen (Biesboer, 1975;Müller and Leenhouts, 1976, Fig.…”

Micromorphology of trichomes in the flowers of the horse chestnut Aesculus hippocastanum L.

“…Their cells exhibited lipid content in the histochemical assays and fluorescence of cell components under the fluorescence microscope. On the fresh flower petals, we did not find clearly coloured, densely distributed glandular trichomes reported in the genus Aesculus by F o r e s t et al [12].…”

“…They are composed of free dimorphic petals (4-5). The two upper petals are narrower than the lateral two [12]. The adaxial surface of the petals bears yellow or carmine spots -nectar indicators (nectar guides), which are larger on the upper petals.…”

“…F o r e s t et al [12] report the presence of densely distributed, different coloured (red, yellow, white) glandular trichomes in the representatives of the genus Aesculus. The trichomes are composed of a multicellular stalk and a multicellular head.…”

Phylogeny and circumscription of Sapindaceae revisited: molecular sequence data, morphology and biogeography support recognition of a new family, Xanthoceraceae

“…The molecular analyses presented here failed to confirm this hypothesis (figs 1 & 2; see below). Instead, they indicate that Handeliodendron belongs to the Hippocastanaceae clade, a placement previously suggested by Forest et al (2001) based on the presence of simple, opposite leaves, whereas Delavaya occupies a basal position within subfam. Sapindoideae along with Ungnadia from Texas and Florida, another genus originally assigned to Harpullieae (these two genera thus forming the Delavaya group; fig.…”