Systematics Of Loganiaceae in West African

ABSTRACT

Loganiaceae is a family of flowering plants classified in the Order Gentianales (Bendre, 1975).

The family was first suggested by Robert Brown in 1814 and validly published by von Martius in

1827 (Nicholas and Baijnath, 1994). Members habits are in form of trees, shrubs, woody climbers

and herbs. Some are epiphytes while some members are furnished with spines or tendrils (Bendre,

1975). They are distributed mainly in the tropics, subtropics and a few in temperate regions

(Backlund et al., 2000). Earlier treatments of the family have included up to 30 genera, 600 species

(Leeuwenberg and Leenhouts, 1980; Mabberley, 1997) but were later reduced to 400 species in 15

genera, with some species extending into temperate Australia and North America (Struwe et al.,

1994; Dunlop, 1996; Backlund and Bremer, 1998). Morphological studies have demonstrated that

this broadly defined Loganiaceae was a polyphyletic assemblage and numerous genera have been

removed from it to other families (sometimes to other Orders), e.g. Gentianaceae, Gelsemiaceae,

Plocospermataceae, Tetrachondraceae, Buddlejaceae, and Gesneriaceae (Backlund and Bremer,

1998; Backlund et al., 2000). The family has undergone numerous revisions that have expanded

and contracted its circumscription, ranging from one genus at its smallest (Takhtajan, 1997; Smith

et al., 1997) to 30 at its largest (Leeuwenberg and Leenhouts, 1980). One of the current

infrafamilial classifications contains four tribes: Antonieae Endl., Loganieae Endl., Spigelieae

Dum. (monotypic), and Strychneae Dum. (Struwe et al., 1994). The tribes Loganieae and

Antonieae are supported by molecular data, but Strychneae is not (Backlund et al., 2000).

Strychneae includes Strychnos Linn. and two Asian genera; Gardneria Wall and Neuburgia

Blume. Spigelia Linn., which is restricted to the western hemisphere, was included in the same

clade as Strychneae in Backlund et al. (2000). There are few molecular phylogenetic studies that