Euphorbia honours the Greek physician Euphorbus who discovered the medicinal uses of the spurges.
Helioscopia refers to the sun.
Petty Spurge; Spurge is from the Latin ex and purgare meaning to purge out and refers to the purgative properties of these plants.
Summary:
A small, hairless, thin leaved, pale green to red stemmed, much branched, erect herb usually less than 40 cm tall. It usually is single stemmed but occasionally has up to 4 stems with acrid, milky sap.
Description:
Cotyledons:
Two. Egg shaped, 5-10 mm long. Tip rounded. Sides convex. Base squarish to rounded. Surface hairless. Petiole shorter than the blade. The seedling has a hypocotyl and short epicotyl.
First leaves:
Paired. 5-12 mm with a 2-3 mm stalk. Hairless. Later leaves tend to arise singly.
Leaves:
Alternate. Does not form a rosette. Leaves are not crowded.
Stipules - None.
Petiole - Short on lower stem leaves but no petiole on leaves subtending branches or floral leaves or bracts.
Blade - Pale green, egg to spoon shaped, cupped, 5-25 mm long by 3.5-11 mm wide, thin. Smooth edges. Hairless.
Floral leaves often tinged with red, broadly egg shaped, usually cupped, 12-15 mm long near the base and smaller near the top.
Stems:
Erect or drooping, 200-700 mm tall, slender, solid with a pithy core, round. Single or branching at the base. Often reddish. Hairless. Milky caustic sap that may burn tender skin.
Flower head:
Yellow green, terminal. 3 much divided rays.
Involucre 1-1.5 mm long, hairless with tiny hairs on the lobes.
Glands crescent shaped with 2 green or yellow horn like appendages on either side.
Flowers:
Small 1-1.5mm. Hairless. At the ends of branches or in branch axils.
Ovary - Styles free or joined at the base, short, deeply split at the tip.
Perianth - None.
Stamens -
Anthers -
Fruit:
3 celled capsule, triangular pyramid, 2 mm long. Each segment furrowed or with 2 wavy keels on the back
Seeds:
Pale grey, 1.5 mm wide, 4 angled with 4 rows of 3-4 dark pits on the back and 2 broad furrows on the inner face. Has an appendage.
Roots:
Taproot.
Key Characters:
Alternate, egg to spoon shaped stem leaves without stipules. Glands of involucre have 2 pointed horn like appendages. Deep regular pits or furrows on the pale grey, four angled seeds.
Sap used in herbal medicine for removing warts and rodent ulcers.
Ornamental.
Detrimental:
Weed of crops, gardens, cultivation and disturbed areas.
Sap is corrosive.
Toxicity:
Toxic but rarely causes problems because it is unpalatable.
Sap causes dermatitis of the skin.
Can burn eyes, especially in children who rub their eyes with sap covered hands.
May cause loss of appetite and loss of egg production in poultry.
Symptoms:
Irritates mucous membranes. Gastroenteritis.
Vomiting and diarrhoea.
Treatment:
Remove stock from infested areas.
Legislation:
None.
Management and Control:
Thresholds:
Little economic importance in Tasmania
Eradication strategies:
Herbicide resistance:
Biological Control:
Very susceptible to orange spored stem rust on stems and leaves.
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) a weed of pineapples is very similar but has red bases on the upper floral leaves.
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)
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)
Sun Spurge (E. helioscopia)
Tree Spurge (E. dendroides)
E. dentata
E. hyssopifolia
Plants of similar appearance:
Very similar to Sun Spurge but usually much smaller with petiolate lower stem leaves with a square cut tip. As a seedling Sun Spurge has serrated leaf tips.
Chickweed (Stellaria media) usually has a line of hairs down the stem and does not exude a white sap when damaged.
Pimpernel (Anagallis arvensis) has a short merging petiole on the cotyledon, the cotyledon is not almost at right angles to its petiole and it has no petioles on its lower leaves. It tends to be low lying.
Waterblinks (Montia fontana) is completely hairless and does not have a midrib groove.
Mouse-eared Chickweed (Cerastium holosteoides) has hairs all over both surfaces of the leaf.
Australian Crassula, Dense Crassula, Spreading Crassula (Crassula spp.)
Four-leaved Allseed (Polycarpon tetraphyllum)
Mouse-eared Chickweeds (Cerastium spp.)
Pearlwort (Sagina apetala)
Pimpernel (Anagallis arvensis)
Pigweed (Portulaca spp.)
References:
Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P161. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P508-509. Diagram.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P245 247. Diagram.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P457. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P271-272.
Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P126, 132.
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). P144-145. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P96-97. Diagrams.
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). #535.19.
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). P450.
Acknowledgments:
Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.