Euphorbia prostrata Aiton (1789: 139)

Mifsud, Stephen, 2018, Contribution to the flora of the Maltese Islands: Euphorbia subg. Chamaesyce and Euphorbia exigua s. l. (Euphorbiaceae), Phytotaxa 372 (2), pp. 153-166 : 159

Euphorbia prostrata Aiton (1789: 139) [ Fig.1D ]

Origin: North America but nowadays widespread as a pantropical and subtropical weed after being introduced in many parts of the Old World ( Smith & Tutin 1968, Steinmann et al. 2016, Hyde et al. 2017, Tropicos 2017)

Occurrences in Europe and the Mediterranean area: Throughout most of south Europe (from the Azores and the Canary islands to Crete and Israel) but apparently missing in north Africa and north Europe ( Smith & Tutin 1968, Euro+Med 2006–2017, DAISIE 2008).

Introduction in Malta: Likely through import of potted plants for horticulture purposes.

Habitat: Roadsides, curbs and paved ground, naturalising locally in urban areas, scarce, but possibly misidentified with other closely related species such as E. serpens .

Invasiveness: Casual occurrence and naturalised locally in few areas but likely increasing where it is found. Invasive potential low, not observed in natural ecosystems.

First record: Not previously recorded, with the exception of Weber & Kendzior (2006) who reported it by mistake (illustration in fact shows a glabrous plant of E. serpens ). Observed by the present author at Baħar iċ- Ċaghaq on 18 September 2014.

Flowering: June–November.

Morphological observations: Density of pilosity varies, but always present as a longitudinal band at the corners of the fruit leaving a glabrous area in between. The seeds with 6–7 transversal ridges is very distinctive for the species.

Chromosome number: 2n = 18 ( Benedì & Orell 1992).

Figures

FIGURE 1. Photos of stipules (left), fruit capsules (centre) and seeds (right) of:A: Euphorbia serpens (EUP03); B: Euphorbia chamaesyce (EUP05); C: Euphorbia maculata (EUP15), D: Euphorbia prostrata (EUP 11); E. Euphorbia hypericifolia (EUP 20). Scale bar = 2mm.