Common name: Asthma Plant
Euphorbia hirta L. APNI*
Synonyms: Chamaesyce hirta (L.) Millsp. APNI*
Euphorbia pilulifera L. APNI*
Euphorbia chrysochaeta W.Fitzg. APNI*
Description: Decumbent to almost erect annual to 40 cm high, few-stemmed with sparse to dense, short curled appressed hairs and long, spreading, yellowish, multicellular hairs.
Leaves rhombic to ovate or sometimes lanceolate, to 40 mm long and to 20 mm wide, margins toothed, apex obtuse to acute, hairy with short appressed hairs, becoming glabrous above; petiole 1–2 mm long; stipules linear.
Cyathia in dense head-like axillary cymes in upper axils; involucre c. 0.7 mm long, glands ovate, reddish with small pink or white appendages or sometimes appendages absent.
Capsule 1–1.2 mm long, 1.5 mm diam., with sparse to dense appressed, shortly curled hairs; seeds ovoid-oblong, c. 1 mm long, red-brown, 4-angled.
Flowering: mainly spring or summer.
Distribution and occurrence: Tropical weed of cultivation, native to Central America.
NSW subdivisions: *NC, *CC, *SC, *NWS, *NWP
Other Australian states: *Qld *W.A. *N.T.
Euphorbia hirta is easily distinguished from the native Australian species by its indumentum of long yellowish coloured hairs on stems and petioles. Euphorbia hirta is very similar to Euphorbia ophthalmica, but E. hirta has a more robust, erect habit with generally larger leaves (to 4.5 cm long) and flower-heads are terminal and axillary.
Text by T.A. James & G.J. Harden, as Chamaesyce hirta in Flora of NSW 1 (1990); notes by S.F. McCune (2020)
Taxon concept: Halford, D.A. & Harris, W.K. (2012), A taxonomic revision of Euphorbia section Anisophyllum Roeper (Euphorbiaceae) in Australia. Austrobaileya 8(4): 497-500; accepted by APC (accessed January 2017)
APNI* Provides a link to the Australian Plant Name Index (hosted by the Australian National Botanic Gardens) for comprehensive bibliographic data
***The AVH map option provides a detailed interactive Australia wide distribution map drawn from collections held by all major Australian herbaria participating in the Australian Virtual Herbarium project.