Hesperis leucoclada Boiss.

AL-Shehbaz, Ihsan A. & Barriera, Gabrielle, 2019, Typification of Edmond Boissier’s Cruciferae (Brassicaceae) names enumerated in Flora Orientalis, Boissiera 72, pp. 1-193 : 71

Hesperis leucoclada Boiss. in Ann. Sci. Nat., Bot. ser. 2, 17: 69. 1842.

 Sisymbrium leucocladum (Boiss.) D.A. German & Al-Shehbaz in Phytotaxa 334: 96. 2018.

Type: “[Aucher-Eloy] N. 4123, Ispahan ”.

Lectotypus (designated here): IRAN: “ Ispahan ”, s.d., Aucher-Eloy 4123 ( G-BOIS [ G00332220 ]; isolecto-: BM [ BM000522181 , BM000522182 ], G [ G00446088 , G00446089 ], K [ K000693872 ], KW [ KW000127972 ], LE [ LE00013085 ], P [ P02272565 , P02272566 , P02272567 ], W [ W0050812 ]) .

Notes. – In addition to the specimen in G-BOIS, BOISSIER (1842a) based the species description on the duplicate P 02272565 that he annotated. Therefore, the lectotypification of DVOŘÁK (1968a, 1968b), which was based on W0050812 that Boissier never examined and which was recently maintained by GERMAN & AL-SHEHBAZ (2018), cannot be accepted.

The generic placement of Hesperis leucoclada has been controversial, and DVOŘÁK (1968a) compared it more with members of the tribe Brassiceae largely because he misinterpreted the incumbent cotyledons with slightly depressed inner one as somewhat conduplicate and eventually placed the species in monospecific Gynophorea Gilli almost solely on having stipitate vs sessile fruit. About a week after the above publication, DVOŘÁK (1968b) retained the species in Hesperis , as was originally placed by BOISSIER (1842a). The species is quite anomalous in Hesperis because it does not have the decurrent stigmas, branched trichomes, and uniseriate multicellular glands characteristic of almost all species of the genus.

Another more realistic placement of H. leucoclada was proposed by KHOSRAVI (2003) based on molecular studies and a closer look at morphology. He transferred the species to the Iranian-endemic Pseudofortuynia Hedge , but neither he nor HEDGE (1968) realized that they were dealing with the same species that they assigned to the tribe Brassiceae . Except for their purple instead of yellow flowers and stipitate vs sessile fruits, a critical closer examination of the type collections at G and W of Hesperis leucoclada and Pseudofortuynia esfandiari Hedge reveals that, they are indistinguishable from Sisymbrium in every morphological character and therefore should be unit-ed with it. It is interesting to note that BOISSIER & BUHSE (1860) described S. hesperidiflorum (see below) and compared it with S. subspinescens Bunge , then Boissier in Flora Orientalis reduced it to synonymy of Hesperis leucoclada .

In conclusion, H. leucoclada was recognized as a member of the tribe Hesperideae ( DVOŘÁK, 1968b) , a member of the tribe Brassiceae ( DVOŘÁK, 1968a; HEDGE, 1968; KHOSRAVI, 2003), and Sisymbrieae ( GERMAN & AL-SHEHBAZ, 2018, and herein). Therefore, the recent synonymy by the last authors of Pseudofortuynia with Sisymbrium is fully justified.