Tribe Gleditsieae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 253. 1943.

Figs 12, 13, 14, 15, 16, 17

Type.

Gleditsia J. Clayton

Included genera

(3). Gleditsia J. Clayton (13 species), Gymnocladus Lam. (6), Umtiza Sim (1).

Description.

Deciduous or evergreen trees, with simple or branched thorns or unarmed; branches with or without lateral brachyblasts. Stipules inconspicuous ( Gleditsia), foliaceous, caducous ( Gymnocladus), or absent ( Umtiza). Leaves bipinnate, pinnate, or intermediate with one or more pinnae replaced by a leaflet. Inflorescences panicles or racemes. Flowers regular, bisexual ( Umtiza), or unisexual and then androdioecious or dioecious ( Gleditsia, Gymnocladus), small, white or greenish to violet, mostly 5-merous; hypanthium short to elongate; calyx gamosepalous; petals small; stamens (6) 10, free; pollen in tricolporate monads, exine perforate, reticulate; ovary sessile or stipitate. Fruit compressed or turgid, papery, leathery or woody, dehiscent, tardily dehiscent or indehiscent, sometimes with pulpy interior, with few to 25 (40) seeds. Seeds compressed to subterete, orbicular or ovoid-elliptic.

Distribution.

Temperate to subtropical North America, South America, Asia, and South Africa.

Clade-based definition.

The most inclusive crown clade containing Umtiza listeriana Sim and Gymnocladus dioicus (L.) K. Koch, but not Ceratonia siliqua L., Dimorphandra conjugata (Splitg.) Sandwith or Mimosa sensitiva L. (Fig. 12).

Notes.

Tribe Gleditsieae was first named by Nakai (1943) to accommodate Gleditsia and Gymnocladus . A close relationship between the two genera has long been known (Polhill and Vidal 1981; Polhill 1994; Lewis 2005b). Gleditsia and Gymnocladus were resolved together with Umtiza, as well as with Tetrapterocarpon Humbert, Arcoa Urb., Ceratonia L. and Acrocarpus Wight ex Arn., in a clade that was informally named the Umtiza clade (Herendeen et al. 2003a, 2003b). The close relationship of Gleditsia, Gymnocladus and Umtiza has been confirmed by Manzanilla and Bruneau (2012), LPWG (2013, 2017) and Ringelberg et al. (2022), but the monophyly of the larger Umtiza clade is not supported (Fig. 12). Umtiza was previously placed in the Cynometra group of tribe Detarieae by Cowan and Polhill (1981) with some uncertainty. The small regular flowers and thorns in Umtiza are notable morphological similarities to Gleditsia . The three genera differ most in fruit structure and dehiscence.