Euphorbia glyptosperma Engelm.

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 : 19

4. Euphorbia glyptosperma Engelm. in Emory, Rep. U.S. Mex. Bound., Bot. 2(1): 187. 1859.

Type (lectotype, designated by Wheeler 1937: 496):— U.S.A. Fort Kearney on the Platte, July 1856, H. Engelmann s.n. ( MO 201313 image!)

≡ Chamaesyce glyptosperma (Engelm.) Small (1903: 712)

Description:—Herbs, annual, with taproot. Stems prostrate, mat-forming, 5–40 cm, glabrous. Leaves opposite; stipules distinct, linear to subulate, usually irregularly fimbriate or lobed, 0.4–2.0 mm, glabrous; petiole 0.2–2.0 mm, glabrous; blade narrowly oblong to oblong-obovate, 3–15 × 2–7 mm, base asymmetric, margins sparsely serrulate, especially near apex, apex rounded to obtuse, abaxial surface usually pale greyish, adaxial surface sometimes with reddish spot, both surfaces glabrous; palmately veined at base, pinnate distally. Cyathia solitary or in small, cymose clusters at distal nodes. Involucre obconic, 0.6–0.9 × 0.3–0.6 mm, glabrous; glands 4, red or purplish, narrowly oblongelliptic, 0.1–0.2 × 0.1–0.5 mm; appendages white to pink, semilunate and fringing distal margin of gland, 0.1–0.3 × 0.1–0.3 mm, distal margin crenulate or lobed. Staminate flowers 1–5. Pistillate flowers: ovary glabrous; styles 0.1–0.3 mm, 2-fid ½ length. Capsules ovoid, 1.3–1.9 × 1.6–2.0 mm, glabrous; columella 1.3–1.5 mm. Seeds with caduceus white coat, testa tan brown, oblong-ovoid, sharply angular in cross section, 1.0–1.4 × 0.6–0.9 mm, with 3–4(–6) prominent transverse ridges that usually interrupt abaxial keel.

Iconography:— Taylor (2016: 24, Figure 5 ), Jercinovic (2007: pl. 10, under the name Chamaesyce glyptosperma ), Fig. 11.

Chromosome number:—2n = 22 ( Steinmann et al. 2016); n = 11 ( Ward 1983); n = 10, 12 ( Urbatsch et al. 1975).

Ecology:—Accidentally dispersed by humans and vehicles as contaminant. It colonizes stream and riverbanks, sand prairies, loess hill prairies, meadows, ballast, open disturbed areas and roadsides ( Steinmann et al. 2016).

Alien status:—Neophyte species native to the New World, it can be considered naturalized in Italy. First European occurrences as casual presences were from Sweden in 1911 ( Blom 1912, 1919) and from Holland in 1916 ( Hügin 1998b). Since the 1964 the species was recorded in Austria ( Hügin & Starlinger 1998), France ( Roux 1992), Republic of Macedonia ( Hügin & Starlinger 1998), Italy ( Hügin & Hügin 1999), Hungary ( Somlyay 2009), Russia ( Geltman & Medvedeva 2017), Romania ( Sîrbu & Șușnia 2018) and doubtfully in Switzerland ( Hügin & Starlinger 1998, Röthlisberger 2007). Its alien status in Europe is uncertain, but it can be considered as naturalized in many cases ( Hügin & Hügin 1999, Tison & de Foucault 2014, Wolf & Király 2014).

Occurrence in Italy:—Naturalized in PIE, LOM and EMR.

Taxonomic annotations:— Euphorbia glyptosperma is similar to E. humifusa , but it can be easily discriminated by seed ornamentation. It can also be confused with glabrous forms of E. chamaesyce .

Figures

FIGURE 5. Euphorbia berteroana:A) exsiccatum from Guadaloupe preserved at TO, B) detail of terminal glomerule with short peduncle (scale = 0.5 mm).