Exostyles

Taxonomy

Exostyles H.W. Schott In K. P. J. Sprengel, Syst. Veg. 4(2): 406. Jan-Jun 1827.

Subfamily: Faboideae.
Phylogenetic Number: 3.1.10.
Tribe: Swartzieae.
Group: Lecointea.
Species Studied - Species in Genus: 0 studied; 2 in genus.

Distribution

Southeastern Brazil.

New World; South America (southeastern Brazil); Brazil and Ecuador.

Generic Notes

We were unable to locate seeds and saw only one intact fruit (Not scored) of E. venusta H.W. Schott ex C.P.J. Sprengel. Seeds and fruits of E. amazonica G.P. Yakovelev are unknown.

Tribal Notes

Tribe Swartzieae

Swartzieae has been assigned to Caesalpinioideae (Cowan, 1968), Swartzioideae (de Candolle, 1825a, 1825b; Corner, 1976), and Faboideae (Bentham, 1865, Hutchinson, 1964, Cowan, 1981). In 1968, Cowan (1968) was unable "finally to resolve the sub-familial relationship of Swartzia," but in 1981, he (Cowan 1981) placed it in the Faboideae and stated, "... features appear to support the arrangement adopted here (Cowan 1981) with the Swartzieae representing a relatively less-advanced position in the Papilionoideae (Faboideae). This conclusion is now supported by wood anatomy ..., by nodulation proclivity ..., and by chemistry ...; chromosome numbers of n=8, 10 or 14 ..., as well as pollen morphology ..., do not negate this conclusion." In the most recent assessment of the Fabaceae, Polhill (1994a, 1994b) maintained Swartzieae as a basal tribe of Faboideae, "transitional to the Caesalpinioideae." He transferred four genera from Sophoreae (2) into the Swartzieae, Amburana (3.1.15), Ateleia (3.1.13), Cyathostegia (3.1.14), and Holocalyx (3.1.12), and arranged the genera in four groups corresponding to clades in Herendeen's (1994) cladistic analysis. Herendeen carried out cladistic analyses using morphological characters of all Swartzieae genera, 19 genera of Sophoreae, and three Caesalpinioideae genera. He concluded that Swartzieae is polyphyletic and that it should be disbanded and its genera transferred to Sophoreae. Preliminary rbcL data (Doyle et al. 1997) supported his conclusions. Ireland et al. (2000) also carried out molecular phylogenetic studies. They also concluded that Swartizeae is polyphyletic, and suggested that possibly tribe Swartzieae could be maintained with Swartzia (3.1.01), Bobgunnia (3.1.01A), Bocoa (3.1.02), Ateleia (3.1.13), Cyathostegia (3.1.14) and the current remaining Swartzieae genera transferred to other tribes. Our seed data neither support nor refute the overall outlines of Herendeen's cladograms; they are discussed below for a few genera. Ferguson and Skvarla (1991) reported on the pollen morphology of Aldina and Swartzia (1.01), and the nine other genera of Swartzieae are covered in Ferguson and Skvarla (1988). Their data are summarized in a computer-generated key in Vezey et al. (1991). The pollen data for the tribe should be compared with our seed-fruit morphological data.