Euphorbia heterophylla Linnaeus (1753: 453)

Silva, Otávio Luis Marques Da, Cordeiro, Inês & Caruzo, Maria Beatriz Rossi, 2014, Synopsis of Euphorbia (Euphorbiaceae) in the state of São Paulo, Brazil, Phytotaxa 181 (4), pp. 193-215 : 200

8. Euphorbia heterophylla Linnaeus (1753: 453) ( Fig. 3A–B ). Lectotype (designated by Radcliffe-Smith in Bosser et al. 1982: 94): — ” Tithymalus Curassavicus, Salicis & Atriplicis foliis variis, caulibus viridantibus ” in Plukenet (1691: t. 112).

Distribution and habitat:— Euphorbia heterophylla is a worldwide tropical and subtropical weed. In the State of São Paulo the species is very common, mainly in disturbed areas.

Representative Specimen:— BRAZIL. São Paulo: São José do Barreiro , 21 January 2013, O.L.M. Silva et al. 75 (SP) .

Taxonomic notes:— Euphorbia heterophylla may be easily identified by having only one cyathial gland, as in E. zonosperma , from which it differs by the absence of indumentum on the involucre, ovary and styles, while these are sericeous or tomentose in E. zonosperma . Euphorbia heterophylla also may be easily recognized in the field by its highly heteromorphic leaves, sometimes with two different shapes (ovate and panduriform, for example) on the same individual.

Euphorbia heterophylla is also similar to E. cyathophora Murray (1786: 81) , which, among specimens from São Paulo, can be easily recognized by the color of the base of the bracts (usually completely green with the very base whitish in E. heterophylla and often red to pinkish at base in E. cyathophora ), the cyathial glands (with round opening in E. heterophylla and flattened in E. cyathophora ), and the seeds (apex acute in E. heterophylla and truncate in E. cyathophora ) (H.-J. Esser, pers. comm.). Euphorbia . cyathophora is an ornamental species only recorded in the State of São Paulo from gardens, as a cultivated species, so it is not covered in this treatment.

Figures

FIGURE 3. A–B: Euphorbia heterophylla. A. habit, B. branch with cyathia. C–E: Euphorbia hirta. C. habit, D. branch with cyathia, E. cyathium. F–H: Euphorbia hyssopifolia. F. habit, G. synflorescence, H. branch with cyathia. Photos: O.L.M. Silva.