Euphorbia engelmannii Boissier, 1860

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 : 15-19

3. Euphorbia engelmannii Boissier , Cent. Euphorb.: 15. 1860.

Type (lectotype, here designated):— [ CHILE]. N °6. Euphorbia Diar. 553. A. s.d., E. F. Poeppig s.n. ( HAL118579 image!), https://herbarium.univie.ac.at/database/detail.php? ID =454120

≡ Euphorbia hortensis Engelm. ex Boissier (1860: 15) , nom. illeg., pro syn.

≡ Euphorbia inclinata Boiss. in Candolle (1862: 42), nom. illeg., pro syn.

≡ Chamaesyce engelmannii (Boiss.) Soják (1972: 169)

Description:—Herbs, annual. Stems prostrate (rarely ascending) with many branches, glabrous generally with a line of appressed hairs. Leaves opposite; stipules triangular to lanceolate fimbriate-laciniate, reddish; blade oblongoblanceolate, base asymmetrical rounded to subcordate, margins entire to slightly crenulate near the apex, apex obtuse to retuse. Cyathia solitary at branches bifurcations to numerous at distal nodes. Involucre conic, glabrous with hairy fauces; bracteoles lanceolate, fringed; glands oblong; appendages short as glands (or shorter) 2–3-lobed. Pistillate flowers: styles free, deeply 2-fid. Capsules smooth, with keeled carpels. Seeds ovoid, slightly rugose with low transverse wrinkles.

Iconography:— Fiori & Paoletti (1901: 303, Fig. 2573), Fig 10.

Chromosome number:—Unknown.

Ecology:—Nitrophyte proper to ruderal communities of trampled biotopes, recorded for roadsides and botanical gardens ( Boissier 1860, Candolle 1862).

Chorology:—Endemic to Chile ( Rodriguez et al. 2018).

Alien status:—Neophyte species native to Chile, recorded in Italy by mistake. E. engelmannii was found in Europe at the beginning of XIX century from plants cultivated in botanical gardens. It is currently recorded as naturalized in France.

Occurrence in Italy:—Absent. Recorded by mistake in PIE, LOM and VEN.

Taxonomic annotations:— E. engelmannii was recorded for the first time in Italy by Jäggi & Schröter (1892) for PIE and by Ascherson (1892) for LOM. Subsequently, Goiran (1895, 1904) reported that his herbarium specimens collected in 1872 in VEN and previously considered of E. chamaesyce var. canescens , corresponded to E. engelmannii . Moreover, Chiovenda (1895) and Fiori & Béguinot(1901) confirmed its presence in Italy.Nevertheless, already Thellung (1907), Fiori & Paoletti (1907) and Fiori (1926) stated that all the previous records corresponded to E. maculata . The occurrence of this species was excluded also for Spain ( Benedì & Orell 1992a) and Switzerland ( Thellung 1907), where the species had been respectively confused with E. serpens and E. maculata . Furthermore, Thellung (1907) suggested that probably this species was not able to spread and maintain a stable population in Europe, and that its records since the half of XIX century should be referred to E. maculata and E. humifusa . The description referred to in this work corresponds to the protologue in Boissier (1860). Nevertheless, some European botanists (e.g. Thellung 1907, Fiori & Béguinot 1901, Chiovenda 1895) referred to a second version proposed by the same author two years later (Boissier in Candolle 1862), and the two descriptions differ for few characters (e.g. glands, stipules, and seeds colour). Thellung (1907) highlighted that E. engelmannii is similar to E. humifusa in habit, but the former is distinguishable for leaves more acute with blade width less than half of the latter.

Type designation:— Boissier (1860) cited in the protologue a specimen collected in San Yago included in E. F. Poeppig exsiccata collection. The specimen here designated as lectotype was collected in Santiago in 1827–1829 and is included in the Poeppig collection, moreover it reports the number 70 which corresponds to the one cited in the protologue of Boissier .