Linnaeus (1753: 456) described Euphorbia exigua providing a short diagnosis “EUPHORBIA umbella trifida: dichotoma, involucellis lanceolatis, foliis linearibus” taken from Wiman (1752: pages 19-20 [species no. 29]), followed by the polynomial “Euphorbia inermis, foliis alternis linearibus acutis, umbella universali trifida, partialibus dichotomis diphyllis” cited from Linnaeus (1738: 199; 1748: 143), Van Royen (1740: 197), Dalibard (1749: 156-157), and associated with the variety acuta, and followed by the synonyms “Tithymalus s.[ive] Esula exigua” cited from Bauhin (1623: 291) and “Esula minima tragi” cited from Dalechamps (1653: 520 [not 1656]).

The protologue also includes the variety retusa cited through the polynomial “Tithymalus s.[ive] Esula exigua, foliis obtusis” cited from Bauhin (1620: 133 [miscited as “132”]; 1623: 291) and indicated with “β”, and followed by the synonym “Tithymalus exiguus saxatilis” cited from Bauhin (1620: 133 [miscited as “132”]; 1623: 291) and Magnol (1676: 259, t. 258), and indicated with the symbol “γ” and followed by the reference “Burs. XVI: 55”. The β and γ indicates that the protologue includes two varieties, the variety β named retusa, and the unnamed γ. The protologue also includes information about the origin of the two varieties: “Habitat in Lusatia, Gallia, Helvetia, Hispania inter segetes; β. Monspelii in saxosis. γ. Paduae & Massiliae”.

Among the original elements, the references to Magnol (1676: t. 258) and Dalechamps (1653: 520) quoted by Linnaeus in the protologue provide illustrations “Tithimalus exiguus saxatilis B prodr” (Fig. 1) and “Esula petite, de Tragus” (Fig. 2), respectively, that can be considered original elements and therefore eligible as lectotype of the name Euphorbia exigua.

Sennikov & Geltman (2013: 178) typified the named variety beta E. exigua var. retusa L. from a specimen collected by Loefling in Spain and preserved at LINN (Löfling 372, Herb. Linn. no. 630.29; image available at https://linnean-online.org/6273/#?s=0&cv=0), and proposed the conservation of E. retusa Forssk. (in Fl. Aegypt.-Arab.: 93. 1775) (type: Egypt, Cairo, 1762, Forsskål 1280, C barcode C10002246) against E. retusa (L.) Forssk. (in Fl. Aegypt.-Arab.: 93. 1775), the basionym of which is E. exigua var. retusa. This proposal was recommended (see Committee for Spermatophyta in Taxon 63: 1361. 2014; Wiersema & al. 2018+), however, the name E. exigua var. retusa may still be used at infraspecific rank if desired.

For the name Euphorbia exigua var. acuta, according to Jarvis (2007), as this varietal epithet is associated with the part of the protologue equivalent to E. exigua (rather than the named and unnamed varieties beta and gamma), it is synonymous with var. exigua, and homotypic with it. However, the polynomial mentioned by Linnaeus “Euphorbia inermis, foliis alternis linearibus acutis, umbella universali trifida, partialibus dichotomis diphyllis” is associated with the name acuta and with the reference of Hortus Cliffortianus (Linnaeus 1738: 199) cited in the protologue from Linnaeus. This reference is also associated with a specimen preserved in the Clifford Herbarium at BM (with barcode BM000628681). The Clifford Herbarium includes plants that were newly cultivated in Europe at the time of collection, as well as specimens from collectors around the world. Linnaeus worked at Clifford’s estate near Haarlem between 1735 and 1737, and described the plants growing there and wrote the Hortus Cliffortianus (1738), a precursor of his Species Plantarum (1753). The specimen BM000628681 can be treated as original material used by Linnaeus to describe his Euphorbia exigua var. acuta (see also Radcliffe-Smith in Meikle 1985: 1443). The sheet at BM bears a complete and well-developed plant, and is annotated “Tithymalus. / minor ex procumbens / H.L. foliis pini / exiguus, erectus / Euphorbia / exigua” (Fig. 3). This specimen is designated as the lectotype of the name Euphorbia exigua var. acuta (see below).

Euphorbia exigua was lectotypified by Jafri & El-Gadi (1982: 39) with the specimen Herb. Linnaeus no. 630.27 (LINN), and this typification was subsequently accepted by Jarvis (2007) and Geltman (2020). The sheet at LINN bears a complete plant, with leaves and flowers, and is annotated “29 exigua” by Linnaeus at the base of the sheet. However, Linnaeus explicitly cited a specimen in the protologue, i.e., “Burs. XVI: 55”, which is currently preserved in Burser’s herbarium (UPS no. V-174929 at UPS-BURSER) in volume XVI: 55 (see also Juel 1923: 99). This specimen is a syntype and, according to Art. 9.12 of the ICN, syntypes have precedence in lectotype designation over other original material (except isotypes) (see Turland & al. 2018). As it is the only syntype, it must inevitably be chosen as the lectotype for this name.

Therefore, according to Art. 9.12 of the ICN, Jafri & El-Gadi’s type, cited by Jarvis (2007), must be replaced by the specimen in the Burser Herbarium, vol. XVI: 55. The sheet Herb. Burser XVI: 55 (UPS no. V-174929) bears two plants, with leaves and flowers, with a label annotated as “V / Tithymalus exiguus saxatilis Baúh. / Prope Monspelium in monte saxoso / unde Bauhino transmisi. / 55.” (Fig. 4).

Juel (1923) comments on some aspects related to the origin and identity of the specimen preserved in Burser’s herbarium, as follows: “BAUH. Prod., 133, sagt von dieser Art nur: ‘circa Monspelium locis asperis provenit.’ LINNÉ führt in Sp. pl. I, 456, BAUH:S Art als Euphorbia exigua γ. an, und zitiert dann: ‘Burs. XVI. 55.’ Seine Angaben über die Fundorte seiner Var. β. und γ. sind verwechselt: ‘Paduas et Massiliae’ gehört zu β., ‘Monspelii in saxosis’ zu γ., wie es aus einem Vergleich mit BAUH. Prodr. hervorgeht. BURS:S Exemplar besteht aus jungen Individuen einer E. exigua L. mit schmalen und spitzen Blättern”.

In conclusion, because Burser’s material at UPS-BURSER (XVI: 55) (now UPS no. V-174929) has been cited in the protologue by Linnaeus, and both (protologue and specimen) are linked, it is syntype (according to the ICN Art. 9.6) and has precedence in lectotype designation over unmentioned specimens (e.g., Herb. Linnaeus no. 630.27 at LINN) and cited illustrations (e.g., “Tithymalus exiguus saxatilis” in Magnol 1676 and “Esula minima tragi” in Dalechamps 1653: 520) according to Art. 9.12 of the ICN. It is therefore the obligate lectotype and accordingly designated here as such.

Fortunately, this specimen clearly represents the traditional concept and current application of the name Euphorbia exigua s. str., showing relevant diagnostic characters of the species (e.g., stem leaves linear, ray and raylet leaves narrowly triangular, slightly enlarged at base) (see, e.g., Prokhanov 1949; Khan 1964; Benedí & al. 1997; Tison & al. 2014; Pignatti 1982). Moreover, the newly designated lectotype does not change the application of the Linnaean name Euphorbia exigua subsp. exigua.

Euphorbia exigua L., Sp. Pl.: 456. 1753 subsp. exigua . Type (lectotype designated here): Herb. Burser XVI: 55 (UPS no. V-174929 [digital image!]). Fig. 4.

Euphorbia exigua var. acuta L., Sp. Pl.: 456. 1753. Type (lectotype designated here): Herb. Clifford 199, Tithymalus 17 (BM, barcode BM000628681 [digital image!]). Fig. 3.

Euphorbia exigua var. retusa L., Sp. Pl.: 456. 1753. Lectotype (designated by Sennikov & Geltman in Taxon 62: 178. 2013): Spain, s.d., Löfling 372, Herb. Linn. no. 630.29 (LINN [digital image!]. Image of the lectotype available at https://linnean-online.org/6273/#?s=0&cv=0

Jafri & El-Gadi (1982: 44) treat two specimens at LINN (Herb. Linn. nos. 630.44 and 630.45) as the type of E. paralias, but none of these specimens in this herbarium are Linnaean original material for this name (Jarvis 2007). Similarly, the specimen Herb. Linn. no. 199.15 (S-LINN) (image available at https://linnaeus.nrm.se/botany/fbo/e/eupho/euphpar2.html.en) indicated by Geltman (2015: 130; 2020: 65) as the “lectotype” is not original material (see Jarvis 2007). This herbarium sheet bears a poorly preserved specimen that is annotated at the base of the sheet as “37. Paralias”, and on the verso as “It. M. Káhl [= Iter Mårten Káhler] / a Linné P. / Paralias”. According to Jarvis (2007: 214-215, 600), this material was sent by Kähler and did not reach Linnaeus until after 1753 (see Jarvis 2007: 214-215, 600). There are more than 50 herbarium sheets of mostly Mediterranean species in the Linnaean Herbarium that Linnaeus received from Mårten Kähler, many of which can be correlated with the manuscript list “Italica Koehleri” in LINN, thought to date from 1757. Among Kähler’s listed names can be found the name E. paralias (image available at https://linnean-online.org/162314/#?#/1&s=0&cv=1&z=-0.0932%2C0%2C1.1865%2C1.6044). Therefore, the “lectotype” designated by Geltman (2015: 130) (see also Geltman 2020: 65) is ineffective according to ICN Art. 9.3.

Linnaeus (1753: 458) described E. paralias providing the diagnosis “EUPHORBIA umbella subquinquefida: bifida, involucellis cordato-reniformibus, foliis sursum imbricatis”, cited from Wiman (1752: page 31 [species no. 53]), followed by three synonyms: (1) “Euphorbia inermis, foliis setaceo-linearibus confertis, umbella universali multifida, partialibus ramose bifidis” cited from Linnaeus (1737: 200 [no. 22]), Van Royen (1740: 193); (2) “Tithymalus maritimus” from Bauhin (1623: 291) and Dodoëns (1616: 370, f. I. 2); and (3) “Tithymalus paralios” from Mattioli (1586: 962). The protologue includes as locality “Habitat in Europae arena maritima”. Mattioli (1586: 962) and Dodoëns (1616: 369, 370) provided illustrations that can be considered original material used by Linnaeus to describe E. paralias and are identifiable with the species.

According to Jarvis (2007: 513), there are three herbarium sheets with specimens that are part of the original material: a sheet is preserved in the Burser Herbarium at UPS (linked to the Bauhin synonyms) (see Savage 1937), another sheet is preserved at Clifford Herbarium at BM (linked to the synonyms taken from Linnaeus’s Hortus Cliffortianus published in 1737 on page 200), and finally there is a sheet preserved in the Linnaean herbarium at S-LINN.

The sheet Herb. Burser XVI(2): 39 (UPS no. V-174912) bears a specimen well-preserved, and a label annotated as “Tithymalus maritimus / Monspelii et Liborni”. The sheet Herb. Clifford: 200, Euphorbia 22 (now barcode BM000628687) bears a complete and well-preserved specimen annotated as “Tithÿmalus / cÿparissias. / paralias / Euphorbia / Cyparissias / 23”, “25”, and “p. 200. Euphorbia 22” (see below).

Finally, the sheet S-LINN 199.13 bears a complete and well-developed plant and is annotated “Euphorbia / 37. Paralias / Sp. pl. 458”, and on the verso “Herb. Alstroemerii / Euphorbia paralias Linn / Dahl a Linné P.” (image available at http://linnaeus.nrm.se/botany/fbo/e/eupho/euphpar1.html.en). Anders Dahl received specimens from both Linnaeus and his son, and also made his own collections in the Uppsala Botanic Garden. Many of these are now to be found in the Linnaean collection at S, annotated with a characteristic form on the verso of each sheet, and often with the words “Dahl a Linne P.”, added by him (Jarvis 2007: 200). Accordingly, S-LINN 199.13 can be considered an original material used by Linnaeus to describe his species, and therefore eligible as lectotype.

Although these three specimens (at BM, UPS and S-LINN 199.13) are undoubtedly original material of E. paralias, the specimen Herb. Clifford: 200, Euphorbia 22 (BM000628687) can be identified as belonging to E. aleppica L. A lectotypification of this name on the plant preserved of this sheet at BM would be nomenclaturally disruptive because this plant is inconsistent with the current usage of the name Euphorbia paralias.

In conclusion, among all the originals elements mentioned, specimens at UPS-BURSER, BM and S-LINN, and illustrations of Mattioli (1586: 962) and Dodoëns (1616: 369, 370), I designate the specimen at S-LINN as the lectotype of E. paralias. This specimen is a complete and informative element, and matches with the traditional concept and current use of the name, showing some diagnostic features (e.g., glabrous, glaucous, somewhat fleshy, leaves 3-30 × 2-15 mm, lowest ones obovate-oblong, middle ones elliptic-oblong and upper ones ovate; all entire, adaxially concave, imbricate; ray-leaves like the upper cauline, raylet-leaves suborbicular-rhombic to reniform, strongly adaxially concave, rays 3-6, glands emarginated) (e.g., Radcliffe-Smith & Tutin 1968; Radcliffe-Smith 1982; Benedí & al. 1997; Tison & al. 2014).

Euphorbia paralias L., Sp. Pl.: 458. 1753. Type (lectotype designated here): Herb. Linn. no. 199.13 (S-LINN; code S 09-28595) (image of the lectotype available at http://linnaeus.nrm.se/botany/fbo/e/eupho/euphpar1.html.en)

In the protologue of E. pinea, Linnaeus (1767: 524) provided, with the number “64”, the phrase name “E. [Euphorbia] umbella quinquefida: dichotoma, involucel. [involucellis] cordatis, fol. [foliis] linearibus acuminates confertis, caps. laeviusculis”. This polynomial is quasi a verbatim copy of either Linnaeus polynomial of E. segetalis (1753: 458) cited from Wiman (1752: page 22 [species no. 34]) “EUPHORBIA umbella quinquefida: dichotoma, involucellis cordatis acutis, foliis lineari-lanceolatis, ramis floriferis”.

The name has been treated as E. pinea or E. segetalis var. pinea (L.) Lange (in Willk. & Lange, Prodr. Fl. Hispan. 3: 499. 1877) (see Riina & al. 2013). However, there is no consensus on the taxonomic value of this taxon, and the name E. pinea is currently treated as a synonym of E. segetalis (Benedí & al. 1997). I was unable to locate any original material in the Linnaean or Linnaean-linked herbaria, and there appear to be no extant original elements (Jarvis 2007). Given the absence of original material its application is clearly uncertain (see Benedí 1997). It is recommended to be rejected as a nomen ambiguum.

Euphorbia pinea L., Syst. Nat., ed. 12, 2: 333. 1767, nomen ambiguum.

Linnaeus (1753: 458) described E. segetalis providing the short diagnosis “EUPHORBIA umbella quinquefida: dichotoma, involucellis cordatis acutis, foliis lineari-lanceolatis, ramis floriferis”, cited from Wiman (1752: page 22 [species no. 34]), followed by five synonyms: (1) “Euphorbia inermis, foliis alternis linearibus acutis, partialibus umbellae ovato-rhombeis, petalis bicornibus” cited from Linnaeus (1748: 142), as “Hort. ups. 142.* [that * is important and something Linnaeus used to indicate that this publication has a detailed description for the species]; (2) “Euphorbia inermis, foliis linearibus acutis ad umbellam quinis isocelibus, ad umbellulas ter dichotomas ovato-trigonis” cited from Sauvages (1751: 46); (3) “Tithymalus annuus, lunato flore, linariae folio longiore” from Morison (1699: 339, sect. 10, t. 2, fig. 3); (4) “Tithymalus maritime affinis, linariae folio” from Bauhin (1623: 291); and finally the synonym (5) “Tithymalus segetum longifolius” from Ray (1724: 312). The protologue includes as locality “Habitat in Mauritania”. Morison (1699: sect. 10, t. 2, fig. 3) provided an illustration (Fig. 5) that can be considered original material used by Linnaeus to describe E. segetalis and is identifiable with the species.

In 1752 was published “Specimen academicum quo Euphorbia ejusque historia naturalis et medica praeside ... Carolo Linnaeo ... sistit Johannes Wiman”, a Dissertation of Johannes Wiman (published by Höjer in Upsala) that was cited extensively by Linnaeus under the Euphorbia species named in Species Plantarum (1753) (see Wiman 1752); the reference there uses the species number in the dissertation (e.g., in this case “Diss. euph. 34”) rather than the page number (Jarvis 2007: 90).

I have not been able to locate any original material in any Linnaean or Linnaean-linked herbaria (see Jarvis 2007). Therefore, the only extant original material eligible for typification of the name E. segetalis is the illustration of Morison (1699: sect. 10, t. 2, fig. 3). Linnaeus’s diagnosis matches with the Morison illustration except for the inflorescences (“umbella quinquefida”) that is not highlighted in the figure. However, this general character is not considered diagnostic of the species as currently recognized. In conclusion, the illustration “Tithÿmalus Linaria folio longiore” published by Morison is designated as the lectotype for the name Euphorbia segetalis (see Fig. 5).

Fortunately, Morison’s illustration matches with the traditional concept and current use of the name, showing some diagnostic features (e.g., leaves linear to linear-lanceolate, entire, ray-leaves elliptic-oblong, raylet-leaves deltate-rhombic, obtuse; base cuneate to subcordate) (see e.g., Prokhanov 1949; Khan 1964; Radcliffe-Smith & Tutin 1968; Radcliffe-Smith 1982; Benedí & al. 1997; Tison & al. 2014).

After searching Robert Morison’s own material of E. segetalis in his herbarium (Morisonian Herbarium, in OXF), a relevant sheet has been found: Morison III. 339 no. 3. However, the Morison Herbarium was not used by Linnaeus, and so Morison’s specimens do not form original material (see Jarvis 2007), but are of interest because they served as voucher specimens for Morison’s illustrations. This sheet contains a specimen with leaves and inflorescences. On the sheet, the label on the bottom left is in the hand of Jacob Bobart the Younger (1641-1719), who was the editor of and primary contributor to volume 3 of Morison’s work. The label is annotated as “Tithymalus annuus lunato flore / Linariaefolio longiore. 3 H. Oxfr. 339. / Tithymalus maritime affinis Linariae / folio. CBP. 291” (Fig. 6). The annotations on the bottom in red and black ink are in the hand of George Claridge Druce (1850-1932), whilst ‘M.P.H. II, 339. no 3 HEFG’ is in the hand of Henry Edward Fowler Garnsey (1826-1903) (Stephen Harris, OXF, pers. comm.). The specimen is clearly identifiable as Linnaeus’s E. segetalis and matches with the current application of the name.

Euphorbia segetalis L., Sp. Pl.: 458. 1753. Type (lectotype designated here): [illustration] “Tithÿmalus Linariae folio longiore” in Morison, Pl. Hist. Univ.: sect. 10, t. 2, fig. 3. 1699. Fig. 5.