Atriplex patula L., Sp. Pl.: 1053. 1753

Iamonico, Duilio, 2012, Studies on the genus Atriplex L. (Amaranthaceae) in Italy. II. Lectotypification of Atriplex elongata Guss., Candollea 67 (1), pp. 181-185 : 184

Atriplex patula L., Sp. Pl.: 1053. 1753 .

Lectotypus (designated by TASCHEREAU, 1972): “Patula 6” s.l., s.d. [before 1753], s.coll. ( LINN [ 1221.19 ]!).

= Atriplex elongata Guss. , Fl. Sicul. Syn. 2: 592. 1844.

Lectotypus (here designated): ITALIA. Sicilia: “Augusta, in argillosis inundatis subsalsis, Septembri-Octobri (ante 1844)”, G. Gussone s.n. (NAP!),

syn. nov. ( Fig. 1 ).

Selected specimens of A. elongata . – ITALIA. Sicily: Trapani, sotto il Monte San Giuliano , XI s.a., G. Gussone s.n. ( NAP) ; Giulia a Agosta, s.d., G. Gussone s.n. ( PAL).

Taxonomic discussion

Based on the description ( GUSSONE, 1844) and the specimens collected by G. Gussone, A. elongata can be included in sect. Teutliopsis Dumort. , the taxa of which arecharacterized by the presence of herbaceous or cartilaginoid fruiting bracts, which are indistinctly veined and have more or less dentate margins ( AELLEN, 1960). In particular, A. elongata seems to be related to A. prostrata DC. [the rejected name A. hastata L. was often misapplied to this species ( TURLAND, 1996), but the name A. hastata in its strict sense refers to A. calotheca (Rafn) Fries , growing along coasts of West and North Europe], to A. patula L. and to A. nilotica Sukhor.

Atriplex prostrata was described by CANDOLLE (1805: 387 “[…] long du canal de Saint-Valery […] aux environs du Hâvre”).According tothe protologue, thisspecies ischaracterized by leaves with prominent lateral lobes and fruiting bractswithout tubercules or spines on the dorsal surface. The lectotypification of A. prostrata was made by GUSTAFSSON (1976) on a specimen kept in G. The same author gives a detailed description of the species, and as to the fruiting bracts, he indicates that they have “[…] the back from smooth to dentate […]”.

Atriplex patula was described by LINNAEUS (1753:1053) “in Europae cultis, ruderatis” as “ ATRIPLEX caule herbaceo patulo, foliis subdeltoideo-lanceolatis, calycibus feminum dicto dentatis” and lectotypified two centuries later by TASCHEREAU (1972).

Several authors (e.g. AELLEN, 1964; PIGNATTI, 1982; CASTROVIEJO,1990; AKEROYD,1993; T AN,1997; J ONSELL,2001; WELSH, 2003; GELIN & al., 2003) considered these species morphologically related, highlighting leaf base features (truncate in A. prostrata vs. cuneate in A. patula ) as diagnostic. The examination of the types (kept in G and LINN) and several other specimens (see the specimina visa) allowed to confirm that this is the only character-state marking the two species. The fruiting bracts are very variable (both in margins and in dorsal surface) and they cannot be used to separate A. prostrata from A. patula .

Recently, the new species A. nilotica (included in sect. Teutliopsis Sukhor. ) was described by SUKHORUKOV (2010) from “Aegyptia, Assuan, ad Nili ripas”. Based on the diagnosis and the examination of the holotype, thisspecies ischaracterized in having the leaves withbase cuneateand margins repandodentate and the fruiting bracts clearly tuberculate.

The found specimens of A. elongata have the fruiting bracts with smooth dorsal surface and proximally entire or dentate margins. The leaves are mostly entire with a cuneate base; only few of them (in the upper part) have two not prominent lateral lobes and obtuse (not truncate) base. Even GUSSONE (1844) indicates “[…] foliis deltoideo-oblongis, infimis hastatis oppositis (paucis) […]” [leaves deltoid-oblong, the lower ones hastate opposite (few)].

Based on these observations, A. elongata seems to be more related with A. patula , although Italian floras ( FIORI & PAOLETTI, 1896-1898; FIORI, 1925; ZANGHERI, 1976; PIGNATTI, 1982) and GREUTER & al. (1984) suggest affinity with A. prostrata . Regarding A. nilotica , A. elongata differs from it in having leaves with entire margins and fruiting bracts with smooth dorsal surface.

Another feature reported in literature to distinguish A. elongata is the leafless inflorescences (see e.g. PIGNATTI, 1982). This character seems to be inconstant (leaves are lacking or are present in the proximal part of the inflorescences both in A. elongata , A. patula and A. prostrata ).

Figures

Fig. 1. – Lectotypus of Atriplex elongata Guss. (indicated by an arrow, the plant on the right). [Gussone s.n., PAL] [© Herbarium Neapolitanum, Università Degli Studi di Napoli Federico II. Reproduced with permission]