Erysimum L.

Erysimum L., Sp. Pl.: 660. 1753.

Tribe: Erysimeae Dumort.

Notes. – BOISSIER (1842a) described the genus Strophades Boiss. and assigned two new species to it. However, he reduced in Flora Orientalis that genus to synonymy of Erysimum.

Erysimum is a well-defined, easily distinguished genus distributed primarily in Eurasia, with fewer species in North America and North Africa. It is taxonomically difficult because there is a general lack of agreement about the total number of species that range from ca. 200 (AL-SHEHBAZ, 2012), 274 (BRASSIBASE, 2019), and substantially higher number (290–350) in the works of POLATSCHEK (2010, 2011, 2012, 2013 a, 2013b, 2014), especially POLATSCHEK & SNOGERUP (2002). Perhaps a more realistic number is something in the neighborhood of ca. 250 species (D.A. German, pers. comm.). The major sources of difficulty are the need of complete plants (with basal leaves, flowers, mature fruits) and the heavy dependence on trichome morphology that often shows tremendous qualitative and quantitative overlap.

As shown below, most of POLATSCHEK’S (2011) typifications of species described by Boissier were based on duplicates at W that Boissier never examined. In the vast majority of cases (almost 95 %), Boissier based his species descriptions on the material in his own herbarium and, therefore, no typification is needed whenever a single collection was cited by Boissier, and the material in G-BOIS has to be the holotype.