Euphorbia hypericifolia Linnaeus, 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 : 23-25

8. Euphorbia hypericifolia Linnaeus, Sp. Pl. 1: 454. 1753.

Type (lectotype, designated by Fosberg & Mazzeo 1965: 199):—[s.l.]. Herb. Linn. 630.4 ( LINN image!)

≡ Anisophyllum hypericifolium (L.) Haworth (1812: 161)

≡ Chamaesyce hypericifolia (L.) Millspaugh (1909: 302)

= Euphorbia hypericifolia var. maculata Klotzsch in Seemann (1856: 276). Type:—Not found.

= Euphorbia boliviana Rusby (1907: 442) . Type :—[ BOLIVIA]. s.d., M. Bang 2907 (holotype NY00263308 image!, isotypes NY00263307 image!, K000253892 image!, US00109300 image!), http://sweetgum.nybg.org/images3/597/109/00263308.jpg

≡ Chamaesyce boliviana (Rusby) Croizat (1946: 291)

= Chamaesyce glomerifera Millspaugh (1913: 377) . Type:— GUATEMALA. Jalapa, El Rancho, 20 January 1908, W.A. Kellerman 8053 (holotype F0055961 F image!), https://fm-digital-assets.fieldmuseum.org/61/581/ V0055961 F.jpg

≡ Euphorbia glomerifera (Millsp.) L.C. Wheeler (1939: 78)

Description:—Herbs, annual, with taproot. Stems erect to ascending, 15–50 cm, glabrous. Leaves opposite; stipules connate, deltate, sometimes laciniate-fringed at tip, 1.5–2.2 mm, glabrous; petiole 1–3 mm, glabrous; blade obliquely oblong, 10–35 × 7–15 mm, base asymmetric, oblique, margins serrate or serrulate, especially toward apex, apex broadly acute, surfaces glabrous; palmately veined at base, pinnate distally. Cyathia in dense, axillary and terminal, capitate glomerules with reduced, bractlike leaves subtending cyathia; peduncle 0.5–1.8 mm. Involucre obconic, 0.9–1.1 × 0.4–0.9 mm, glabrous; glands 4, yellow-green to brown, subcircular, 0.2 × 0.2 mm; appendages white to pink, shape highly variable, usually round to elliptic, 0.3–0.4 × 0.5–0.7 mm, margin entire. Staminate flowers 2–20. Pistillate flowers: ovary glabrous; styles 0.4 mm, 2-fid ½ length. Capsules globoid, 1.3–1.4 × 1.1–1.5 mm, glabrous; columella 1.0– 1.1 mm. Seeds light brown, with very thin coat, ovoid-triangular, slightly 4-angled in cross section, 0.9–1.1 × 0.5 mm, with shallow irregular depressions alternating with low, smooth ridges.

Iconography:—Atha et al. (2018: 2–3, Figs. 1–2), Fig. 15.

Chromosome number:—2n = 32 ( Ma & Gilbert 2008); n = 8 ( Trivedi & Trivedi 1992); 2n = 16 ( Krishnappa & Reshme 1980); 2n = 28 ( Hans 1973); n = 14, 28 ( Hans 1973); 2n = 56 (Gill et al. 1970).

Ecology:—Accidentally dispersed by humans as contaminant; globally considered as weed of orchards and plantations. Typical of open and disturbed areas ( Steinmann et al. 2016), it also colonizes flowerbeds and roadsides.

Alien status:—Neophyte species native to the New World tropics, it can be considered naturalized in Italy. The first record in Europe was as casual for Belgium in 2002, and subsequent for Spain (with uncertain degree of naturalization) and Greece ( Sutorý & Verloove 2015). It was recently recorded in Italy by Banfi & Galasso (2014, under the name E. hyssopifolia ), and subsequently by Sciandrello et al. (2016).

Occurrence in Italy:—Casual in TOS, PUG ( Galasso et al. 2018b) and SAR ( Campus 2018); naturalized in SIC; recorded by mistake in LOM.

Taxonomic annotations:— Euphorbia hypericifolia can be confused with E. hyssopifolia , especially for similar habit and leaf morphology ( Mugnai et al. 2018, Galasso et al. 2018b). In E. hypericifolia cyathia are subtended by reduced, bractlike leaves and grouped in capitate glomerules (see Fig. 12), while E. hyssopifolia is characterized by solitary cyathia or in small cymose clusters at distal nodes or on congested, axillary branches ( Steinmann et al. 2016). Euphorbia hypericifolia also differentiates from E. hyssopifolia for its complete glabrescence, larger stipules and smaller seeds. This species has been also confused with E. nutans (see taxonomic annotations of E. nutans ). The record for SAR by Campus (2018) had been formerly attributed to E. hyssopifolia and subsequently corrected as E. hypericifolia . Through the analysis of the images we confirm the identification of E. hypericifolia .

Type designations:—According to Jarvis (2007), the correct typification for E. hypericifolia is the one by Fosberg & Mazzeo (1965), which predates the one by Burch (1966). Previously, Wheeler (1939) had incorrectly treated 630.3 ( LINN image!), a Browne collection not received by Linnaeus until 1758, as the type.

Klotzsch (in Seemann 1856), in the protologue of Euphorbia hypericifolia var. maculata , cites a specimen collected by Potts at Chihuahua ( Mexico). We could not identify any specific collection of Poots (this name can be referred to various botanists), nor we could find any eligible specimen in Klotzsch’s collection (mainly in B) .