“…in Genisteae, Thermopsideae and Crotalarieae (Metcalfe and Chalk, 1950;Yatsenko-Khmelevsky, 1954;Grosser, 1977;Baretta-Kuipers, 1981;Fahn et al, 1986;Schweingruber, 1990;Van Wyk and Schutte, 1995;InsideWood, 2004-onwards;Schweingruber et al, 2011;and our unpublished observations) as well as in some members of the tribes Sophoreae (Gasson, 1994), Hedysareae (Benkova and Schweingruber, 2004); Galegeae (Fahn et al, 1986), Loteae (Schweingruber et al, 2011) and the subfamily Caesalpinioideae (Cozzo, 1951;Schweingruber et al, 2011). This trend can be postulated to be an adaptation to water stress, because the vessel groups provide the bypass water conduits in the case of an embolism of some vessels (Zimmermann, 1983;Carlquist, 1987;Sperry, 2003).…”