Euphorbia nutans Lagasca y Segura, Gen. Sp. Pl.

Mugnai, Michele, Lazzaro, Lorenzo, Nuzzo, Luca Di, Foggi, Bruno, Viciani, Daniele & Ferretti, Giulio, 2021, Synopsis of Euphorbia section Anisophyllum (Euphorbiaceae) in Italy, with an insight on variation of distribution over time in Tuscany, Phytotaxa 485 (1), pp. 1-65 : 30-32

12. Euphorbia nutans Lagasca y Segura, Gen. Sp. Pl. : 17. 1816 b.

Type (lectotype, here designated):— SPAIN. Hort. Reg. Matr., 1815, J. D. Rodriguez s.n. ( MA 250449 image!, isolectotype MA250449-2 image!), https://www.gbif.org/occurrence/1936037727

≡ Tithymalus nutans (Lag.) Sampaio (1931: 45)

≡ Chamaesyce nutans (Lag.) Small (1903: 712)

= Euphorbia preslii Gussone (1827: 539) . Type (lectotype, here designated):— ITALY. Palermo , Boccadifalco , August s.d., Gussone s.n. (NAP! individual on the right), Fig. 20

≡ Chamaesyce preslii (Guss.) Arthur (1911: 260) ≡ Euphorbia trinervis Bertoloni (1842: 37) nom. illeg. = Euphorbia hypericifolia var. communis Engelm. in Emory (1859: 188). Type (lectotype, here designated):—[ MEXICO]. 1851–

1852, C. Wright 1842 ( US 00109374 image!, isolectotypes NY00263134 image!), https://collections.nmnh.si.edu/media/

?ark=210fe75b63934e85afcd3113cebd6d0a – Euphorbia hypericifolia subsp. indica auct., non (Lam.) Pignatti (1982: 35), comb. inval.

Description:—Herbs, annual, with taproot. Stems usually ascending, occasionally erect, 20–80 cm, sparsely pilose, hairs often concentrated at nodes and distally, occasionally in 2 bands along opposite sides of stem. Leaves opposite; stipules distinct to connate, irregularly fringed, or divided, 1.0– 1.5 mm, villous; petiole 0.3–1.6 mm, moderately pilose; blade oblong to oblong-lanceolate, 8–40 × 3–12 mm, base asymmetric, margins serrulate, apex angled with blunt tip, abaxial surface pale green or reddish, adaxial surface usually reddish or with conspicuous reddish spot, both surfaces usually sparsely pilose, especially toward base, sometimes glabrous; 3–5-veined from base, pinnate distally, veins faint. Cyathia solitary at distal nodes or in small, cymose clusters at branch tips; peduncle 0.5–2.5 mm. Involucre narrowly obconic, 0.5–1.0 × 0.3–0.7 mm, glabrous; glands 4, green to reddish purple, oblong to subcircular, 0.2–0.4 × 0.3–0.5 mm; appendages white or pinkish, ovate to elliptic, 0.2–1.0 × 0.2–1.5 mm, margin entire. Staminate flowers 5–28. Pistillate flowers: ovary glabrous; styles 0.6–2.5 mm, 2-fid ½ length. Capsules ovoid, 1.6–2.3 × 1.5–2.4 mm, glabrous; columella 1.4–1.6 mm. Seeds dark brown, with thin coating, elliptic-ovoid, rounded-angular in cross section, 1.0–1.6 × 0.5–0.8 mm, surface finely and irregularly wrinkled, sometimes with indistinct, shallow, rounded cross ridges.

Iconography:— Pignatti et al. (2017: 325), Jercinovic (2007: Tab. 17, under the name Chamaesyce nutans ), Benedì (1997: Fig. 71, under the name Chamaesyce nutans ), Fig. 21.

Chromosome number:—2n = 12, 14, 22 ( Steinmann et al. 2016); n = 20 ( Mulligan 1984); n = 6 ( Urbatsch et al. 1975).

Ecology:—Accidentally dispersed by humans and escaped from cultivations where it is present as contaminant; globally considered as weed of cereals, orchards, plantations, vegetables and pastures. This species is very common also along railways and on rocky riverbeds and pond edges ( Steinmann et al. 2016).

Alien status:—Neophyte native to the North America, reported as invasive in Italy ( Galasso et al., 2018a). It was historically recorded (probably from first decades of XIX century) in Europe with a current distribution in middle, southwestern and southeastern Europe. Saccardo (1909) includes the species among species in XVIII century, while first Italian records are probably from VEN, according to Thellung (1907) in 20s of XIX century, and LOM ( Lanfossi 1825, Banfi & Galasso 2010).

Occurrence in Italy:—Naturalized in PIE, TAA, FVG, LIG, EMR, TOS, MAR, UMB, LAZ, ABR, CAM and SIC; invasive in LOM and VEN; casual in PUG and CAL. In Galasso et al. 2018a the status of the species for TOS is casual. However, according to the extensive analysis of herbarium material and field investigation, we consider the species as naturalized in TOS.

Taxonomic annotations:— Euphorbia nutans shows affinities with E. hypericifolia and E. hyssopifolia , especially due to its habit and overall size. However, E. nutans differs from the others for distribution of stem hairs in lines (see Fig. 20).

Type designations:—Several authors reported information on the type material of E. nutans ( Parolly & Eren 2007, Radcliffe-Smith 1985, Wheeler 1941), but all of them reported only protologue information (mainly the annotation “Habitat in N [ova] H [ispania]”) not citing any specific specimen. Lagasca y Segura (1816a) included E. nutans in a list of species cultivated in botanical garden of Madrid (“ Elenchus plantarum , quae in horto regio botanico matritensi colebantur ”). The list is followed by further 35 pages (printed as pp. 1–35) containing the diagnosis of new or poorly known species (Generum specierum que plantarum novarum aut minus cognitarum diagnoses), including the protologue of E. nutans . This text was also issued separately as Lagasca y Segura (1816b), which is assumed to have been published almost simultaneously with the Elenchus (see Stafleu & Cowan 1983). In MA are preserved three specimens of E. nutans collected in the botanical garden of Madrid prior to 1816 ( MA 250449, MA 250449- 2, MA 250299). Considering that the author included this species in the Elenchus , it seems reasonable that he used these specimens for the species description and are eligible as type material. The specimen designated as lectotype material is the one that contain more information: it includes many labels reporting both original determination (“ E. hypericifolia L., E. … nutans ”) and collection data ( J.D. Rodriguez in 1815 in “Hort. Reg. Matr.”). In MA are also preserved specimens collected in the species locus classicus (Nova Hispania) by Sessé and Mociño between 1787 and 1804 ( MA 602262, MA 602263, MA 602264, MA 602265, MA 602266) that Lagasca probably viewed and used for the delimitation of locus classicus (see Lagasca y Segura 1816a, 1816b).

The specimen chosen as lectotype of the name E. preslii was collected in the locus classicus (Palermo) and the label is handwritten by Gussone but lacks the collection date. According to La Valva (1993), all Gussone’s exsiccata used for the publication of Prodomus ( Gussone 1827) lack the collection date.

Engelmann (in Emory 1859), in the protologue of E. hypericifolia var. communis refers to Wright’s specimen n. 1842 (in part), as if the sheet were including more species. Indeed, Wheeler (1941) reported that the specimen was a mixture of two species and separated the original US specimen into two, one being an isotype of E. hypericifolia var. communis , the other one being the type of E. pilulifera var. discolor Engelm. in Emory (1859: 188) (a heterotypic synonym of E. hirta ). Wheeler (1941) also indicated as type material a specimen probably in M that he could not find (“ M? not found”), and two duplicates specimens in US e NY (“isotypes”). Unfortunately, there are no elements in the protologue that make it clear which portion of Wright’s sample Emory was referring to, thus no holotype can be individuated.Accordingly, still following Wheeler (1941), we here designated as lectotype the specimen US 00109374, which corresponds to the description of a mixture exsiccata provided by Engelmann in the protologue, and the specimen NY 00263134 as isolectotype.