Equisetum hyemale Linnaeus (1753: 1062)

Ferrer-Gallego, P. Pablo, Laguna, Emilio & Rosselló, Josep A., 2017, Typifications of the Linnaean name Equisetum hyemale and E. × moorei (Equisetaceae), Phytotaxa 305 (2), pp. 104-110 : 105-106

Equisetum hyemale Linnaeus (1753: 1062) .

Type (lectotype, designated here):—[icon] “ Equisetum ” in Mattioli (1586: 770, f. A) (Image available at: https://bildsuche.digitale-sammlungen.de/index.html?c=viewer&bandnummer=bsb00089694&pimage=00784&lv=1&l=es) ( Fig.1 ). (epitype, designated here): Herb. Linn. No. 1241.7 ( LINN) (Image available at: http://linnean-online.org/12435/).

Linnaeus’s protologue (1753: 1062) consisted of a nomen specificum legitimum “ EQUISETUM caule nudo scabro basi subramoso” cited from an early Linnaean work (1745: 838 [page 305]) and Dalibard (1749: 308), followed by five synonyms, and the locality “ Habitat in Europae sylvis, asperis, uliginosis ” and the symbol “4” [perennial plant]. The first synonym, “ Equisetum scapo nudo simplicissimo”, was cited from Van Royen (1740: 496) and Gronovius (1739: 196); the second, “ Equisetum hyemale ” from an early Linnaean work (1737: 394 [page 311]); the third, “ Equisetum foliis nudum ramosum”, from Bauhin (1623: 16); the fourth, “ Equisetum nudum minus variegatum basiliense”, from Bauhin (1623: 16, prod. 25); and the fifth, “ Equisetum ” from Mattioli (1586: 770, f. A). Only one of these synonyms was accompanied by an illustration ( Mattioli 1586) that could be considered as original material ( Fig.1 and image also available at: https://bildsuche.digitale-sammlungen.de/index.html?c=viewer&bandnummer=bsb00089694&pimage= 00784&lv=1&l=es).

Only one herbarium specimen is considered as original material by Jarvis (2007: 497): Clayton 657, pl. 2 ( BM, with barcode BM 000062952) (image available at: http://www.nhm.ac.uk/resources/research-curation/projects/ clayton-herbarium/lgimages/ BM 000062952. JPG). The sheet contains a single vegetative stem, and two labels, (a) “ Virginia Clayton Ex Herb. Gronova” (printed label), and (b) “ Equisetum scapo nudo simplicissimo Roy. Prodr. p. 496 / Equisetum non ramosus Clayton n. 657 pl. 2 / Equisetum hyemale Linn fl. Lapp. p. 394 / Equisetum foliis nudum non ramosum C. B.p. 16 / Equisetum caules scabro basi subramosus Linn Syst. gen. 1033 n. 6” handwriting by John Clayton.

Gronovius was in possession of an extensive collection of Virginian material collected by John Clayton, the basis for Gronovius’s Flora Virginica. When Linnaeus was in the Netherlands during 1735–1738, he was able to study much of Clayton’s material. However, he acquired only a selection of duplicates for his own herbarium, chiefly via Gronovius and Peter Collinson ( Stearn 1957: 108). The Clayton herbarium of Gronovius was later acquired by Banks in 1794 and it is now held at BM ( Jarvis 2007: 198–199, 208).

Therefore, the provenance of the specimen preserved at BM is in conflict with the protologue, because Linnaeus cited “ Habitat in Europae … ” and this material was collected in Virginia ( United States of America). The typical form of E. hyemale [ subsp. hyemale ] occurs in Europe and Asia to northwestern China in Xinjiang ( Tutin 1964, Hauke 1993), but it is absent from North America where it is replaced by subsp. affine (Engelmann) Calder & Taylor (1965: 1387) (see Hauke 1962, 1993). Accordingly, the Clayton 657, pl. 2 specimen ( BM) does not fit the current concept and use of the name E. hyemale s. str., and therefore it is not suitable for lectotypification.

We have been unable to trace any further original material in any of the other Linnaean or Linnaean–linked herbaria (e.g., at L, which would be linked to the synonym by Van Royen (1740) or at UPS which would be linked to the synonym by Bauhin (1623) cited by Linnaeus in the protologue).

Fortunately, Mattioli’s illustration (1586: 770, f. A) is eligible to serve as lectotype, and it is therefore designated here as such.This illustration shows two monomorphic aerial stems with strobili ( Fig.1 ), and it is the original element that shows the best matches with the traditional concept and current usage of the Linnaean name E. hyemale . Furthermore, an epitype is here designated as recommended by the Art. 9.8 of the ICN ( McNeill et al. 2012), in order to avoid any eventual ambiguity coming from the taxonomic interpretation of the lectotype. This is further supported by the fact that the lectotype does not clearly show fine diagnostic characters which are essential to distinguish E. hyemale from other nothospecies where this species is involved in their origin, i.e., E. × moorei Newman (1854: 19) [ E. hyemale × E. ramosissimum Desfontaines (1799: 398–399) ] morphologically very close to E. hyemale , and E. × trachyodon Braun (1839: 305) , pro sp. [ E. hyemale × E. variegatum Schleicher ex Weber & Mohr (1807: 447) ].

Some features present in E. hyemale , e.g., ridges with 2 rows of tubercles separated without cross–bands, (with cross–bands of silica covering the ridges in E. × moorei ), teeth of leaf–sheaths very soon deciduous, and fertile spores have been considered essential to distinguish E. hyemale from these two hybrids (see Schaffner 1931, Hauke 1962, Tutin 1964, Bennert et al. 2005, Jepson et al. 2013, Feoktistov & Gureyeva 2016). Moreover, the most visible diagnostic characters are those from leaf sheaths ( Stace 2010), preferably observed in the middle part of the shoots ( Pétrement et al. 2012, Kalinowski et al. 2016). Thus, in E. × moorei the length/width ratio of the leaf sheets is 2 or more (up to 2.3) and showed a narrow black stripe at the base. In contrast, the E. hyemale sheets show a ratio ca. 1 (up to 1.5) and a conspicuous broad stripe is present.

These discriminant characters can be seen on the specimen of E. hyemale in the specimen at Herb. Linn. No. 1241.7 ( LINN) herein proposed as the epitype. This sheet is annotated “ hyemale ” by Linnaeus and the specimen was identified as E. hyemale by Hauke (1962), and clearly represents the traditional concept (e.g., Linnaeus 1753, Newman 1854, Milde 1867) and current use of the name E. hyemale (e.g., Hauke 1962, 1963, Tutin 1964, Prada 1986, Bennert et al. 2005, Pétrement et al. 2012, Jepson et al. 2013, Feoktistov & Gureyeva 2016, Kalinowski et al. 2016).

Figures

FIGURE 1. Lectotype of Equisetum hyemale Linnaeus, [icon] “Equisetum” in Mattioli (1586: 770, f. A).