Decaisnea Hooker & Thomson
Decaisnea comprises one or two species, depending on taxonomic opinion. In a recent monograph Christenhusz (2012) accepted two species: Decaisnea insignis (Griffith) Hook.f. & Thomson is known from Bhutan, Burma and northern India, while Chinese and Nepalese plants have been distinguished as D. fargesii Franchet. Both are only reliably separated on fruit color, i.e.: yellow-green in D. insignis and bluish in D. fargesii. The latter also tends to have smaller leaves with less numerous leaflets (to 100 cm long with 13-15 leaflets, vs. to 200 cm with 15-23 leaflets in D. insignis; see Christenhusz l.c.). Other recent authors (e.g. Chen & Shimizu 2001) recognized a single, variable species. For nomenclatural reasons, in this case the older name D. insignis should be applied.
One species of Decaisnea has been recorded as an escape from cultivation in Belgium. Since it does not (yet) produced fruit in its single locality it is here referred to as D. insignis s.l., incl. D. fargesii. However, since Decaisnea is chiefly cultivated for its attractive bluish fruits, plants in cultivation probably mostly belong to D. fargesii (provided that both species were accepted). It probably is the only species that is sufficiently hardy for cultivation out-of-doors in large parts of western Europe (Christenhusz 2012).
Chen D. & Shimizu T. (2001) Lardizabalaceae. In: Wu Z.Y. & Raven P.H. (eds.), Flora of China, vol. 6. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis: 440-454. [available online at: http://flora.huh.harvard.edu/china/mss/volume06/Lardizabalaceae.pdf]
Christenhusz M.J.M. (2012) An overview of Lardizabalaceae. Curtis's Botanical Magazine 29(3): 235-276.
Matthews V.A. (1989) Lardizabalaceae. In: Walters S.M. & al. (eds.), The European Garden Flora, vol. 3: 396-398.