Staphylea L.

Thirteen species of deciduous shrubs to small trees, usually with multiple stems from the base. Leaves opposite, with 3–5(–7) leaflets, the terminal leaflet having a longer petiolule, leaflets oblong to elliptic, sometimes asymmetric (especially the lateral leaflets), glabrous to slightly pubescent, margins toothed, apex rounded to sub-acuminate (especially the terminal leaflet); stipules, linear and papery, soon falling. Inflorescence a terminal panicle, thyrse or raceme, borne on second-year wood and subtended by short bracts, with few to many (25+) flowers on short pedicels. Flowers hermaphrodite, appearing slightly before or as the leaves expand, with five equal sepals surrounding five equal petals that form a narrow or wider tube; the five stamens are inserted at the base of the petals but often exceed the corolla tube; ovary with two or three locules and styles that may or may not be united, with several ovules per locule. Capsule inflated and bladder-like, becoming dry and stiffly-papery, persisting through the winter, dehiscing at the apex of each section; seeds shiny, yellow to brown. (Bean 1981, Brouillet 2015, Li, Cai & Wen 2008).

Fossil records indicate an ancient origin for the Staphyleaceae (the only other member of the family, Dalrymplea, is tropical), with seeds attributable to extant taxa having been found in Tertiary deposits (Christenhusz, Fay & Chase 2017). This antiquity explains the current interesting distribution of Staphylea; although it occurs across Eurasia and North America the species are often widely geographically separated. There is a small concentration in China, though some taxa are locally endemic and have not been introduced (S. yuanjiangensis K. M. Feng & T. Z. Hsu (Yunnan), S. campanulata J. Wen (Sichuan), S. shweliensis W. W. Smith (NW Yunnan), S. forrestii I. Balfour (WC China), described as being a tree to 17 m! (Flora of China). The west Himalayan and Afghan taxon known as S. emodi Wall. is poorly understood. The Mexican species are also little known and seldom cultivated, though S. pringlei S. Watson is grown at the University of California Botanical Garden at Berkeley from several collections made in Tamaulipas during the 1990s (https://webapps.cspace.berkeley.edu/botgarden/search/search/). It appears to be similar to S. holocarpa.