2. Ribes divaricatum Douglas (western N-Am.) – An exceptional but locally well-established escape from cultivation. Discovered in 2010 in deciduous woodland in Baudour (Bois de Baudour, Quartier de la Charbonnière): several bushes in the vicinity of the former garden of F. Buxant, along with Photinia villosa and others. In 2014 also seen in woodland in Eksel.
Ribes divaricatum much resembles native R. uva-crispa and might have been overlooked. In addition to the characters mentioned in the key, it usually has 5-lobed leaves with lobes that are mostly lobed again (leaves merely 3-5 lobed in Ribes uva-crispa). Moreover, its thorns are often longer and slightly bent or hooked at apex.
The identification of Ribes divaricatum with (horticultural) standard floras turned out to be difficult. Several characters proved to be unreliable, for instance leaf pubescence (De Koning & al. 2000, Roloff & Bärtels 2006). It is not impossible that plants in horticulture represent hybrids.
In Europe Ribes divaricatum is a rare escape from cultivation (by far best known from Scandinavia; see Lye 1992, Karlsson 2002). It recently also occurred in the British Isles (Stace 2010).
Ribes divaricatum
Ribes uva-crispa
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Selected literature
De Koning J., Van den Broek J.W., Van de Laar H.J. & Fortgens G. (2000) Nederlandse dendrologie (13e druk). H. Veenman & zonen, Ede: 585 p.
Karlsson T. (2002) Nyheter i den svenska kärlväxtfloraen II. Korsblommiga-flockblommiga. Svensk Bot. Tidskr. 96(3-4): 186-206.
Lye K.A. (1992) Spärrkrusbär, Ribes divaricatum, naturaliserad i Skandinavien. Svensk Bot. Tidskr. 86(4): 275-279.
Roloff A. & Bärtels A. (2006) Flora der Gehölze (2e Auflage). Ulmer, Stuttgart: 844 p.
Sinnott Q.P. (1985) A revision of Ribes L. subg. Grossularia (Mill.) Pers. sect. Grossularia (Mill.) Nutt. (Grossulariaceae) in North America. Rhodora 87: 189-286.
Stace C. (2010) New flora of the British Isles, 3th ed. Cambridge University Press.