Euphorbia honours the Greek physician Euphorbus who discovered the medicinal uses of the spurges.
Helioscopia refers to the sun.
Sun Spurge; Spurge is from the Latin ex and purgare meaning to purge out and refers to the purgative properties of these plants.
Summary:
An erect, annual plant that is usually 35 to 45 cm tall at maturity and may have more than one stem arising from the base which exudes white sap if damaged. The leaves are alternate, spoon shaped, 1-4 cm long and toothed near the tips.
Description:
Cotyledons:
Two. The cotyledon has a blade 7-10 mm long with a short petiole 3-4 mm long. Tip rounded. Sides convex. Base tapered. Surface hairless. The seedling has both a hypocotyl and an epicotyl.
First leaves:
The early leaves are paired, the pairs being at right angles to each other, but as the plant grows the leaves become single. The early leaves are 10 to 15 mm long, sessile and hairless, and do not usually persist in the mature plant.
Leaves:
Alternate, does not develop as a rosette.
Stipules - None.
Petiole - Virtually none.
Blade - Dark green and pale on the lower part of the midrib, spoon to wedge shaped, 10-40 mm long by 8-17 mm wide. Tip obtuse or rounded. Sides convex to straight angular with fine teeth on the edges near the top. Base tapered. The upper floral leaves are shorter, broader and stalkless.
Stems:
Circular in cross section, solid, up to 500 mm tall, and hairless or sparsely covered in fine long hairs. It may have more than one stem arising from the base. Towards the top the stems branch, these branches themselves becoming sub-divided. Where branching occurs there is a group of hairless, sessile leaves, one for each branch. There are 3-5 fertile branches for each stem. When cut the plant exudes a sticky white latex.
Flower head:
Umbel of 5 long rays that are 3 forked then 2 forked. Flower head (involucre) 2 mm long, hairless outside and hairy inside. Involucre lobes hairless. Bracts broadly elliptic to broadly egg shaped, often finely toothed with one larger than the other.
Flowers:
The flowers are terminal on axillary branches. Individual flowers are very small.
Ovary - Slender style, scarcely divided.
Perianth -
Stamens -
Anthers - Cells distinct, transversely elliptic.
Glands, yellow or white, transversely elliptic, entire.
Fruit:
Capsule, triangular pyramid with 3 rounded lobes, smooth, 3-5 mm long by 2-3 mm wide, hairless, one seeded.
Seeds:
Dark brown, egg shaped, 2 mm long, pitted network patterned, with a fleshy appendage.
Roots:
Taproot.
Key Characters:
Stem leaves are alternate, without stipules and spoon shaped. Glands entire. 5 rays in the umbel. Annual.
Biology:
Life cycle:
Annual. Germination occurs in Autumn and Spring.
Physiology:
Reproduction:
By seed.
Flowering times:
August to December in SA.
August to October in Perth.
Seed Biology and Germination:
Vegetative Propagules:
Hybrids:
Allelopathy:
Population Dynamics and Dispersal:
Origin and History:
Europe, central and eastern Asia.
Distribution:
ACT, NSW, QLD, SA, TAS, VIC, WA.
Sun Spurge is locally common in the South and North-West of Tasmania, but less common in the North where the very similar Petty Spurge is prevalent.
Habitats:
Climate:
Temperate.
Soil:
Plant Associations:
Significance:
Beneficial:
Ornamental.
Detrimental:
Weed of disturbed areas.
It is a species of waste areas and has little economic significance in Tasmania.
Toxicity:
Toxic to sheep, cattle and man.
Potentially of some danger to children and may cause dermatitis.
Symptoms:
Gastro enteritis.
Treatment:
Remove stock from infestations.
Legislation:
None.
Management and Control:
Thresholds:
Eradication strategies:
Herbicide resistance:
Biological Control:
Related plants:
Asthma plant (E. hirta)
Bottle tree Caustic (E. stevenii)
Caper Spurge (E. lathyrus)
Caustic weed (E. drummondii)
Climbing Caustic (E. sarcostemmoides)
Cypress Spurge (E. cyparissias)
Desert Spurge (E. tannensis ssp. eremophila)
Dwarf Poinsettia (E. cyathophora)
Dwarf Spurge (E. exigua)
Eyebane (E. maculata)
False Caper (E. terracina)
Garden weed (E. segetalis)
Gascoyne Spurge (E. boophthona)
Hairy Caustic Weed (E. australis)
Mexican Fire plant (E. heterophylla)
Naked Lady (E. tirucalli)
Petty Spurge (E. peplus) doesn't have serrated leaf tips.
Plains Spurge (E. planiticola)
Poinsettia (E. pulcherrima)
Red Caustic creeper (E. prostrata)
Red Caustic Creeper (E. thymifolia)
Sea Spurge (E. paralias)
Sickle leaved Spurge (E. falcata)
Snow on the Mountain (E. marginata)
Tree Spurge (E. dendroides)
E. dentata
E. hyssopifolia
Plants of similar appearance:
Sun Spurge can be distinguished from Petty Spurge in the seedling stage by the serrated leaf tips, those in Petty Spurge being plain. The mature plant is much larger than petty Spurge and can be distinguished by it larger inflorescence.
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P161-162. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P509.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P268.
Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P130.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P96-97. Diagrams.
Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P144. Photo.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #535.11.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P449.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.