Prickly Paddymelon

Cucumis myriocarpus Naudin

Family: - Cucurbitaceae.

Names:

Cucumis is the Latin name for cucumber, a close relative of Prickly Paddymelon.
Myriocarpus is from the Greek myrias or Latin myrio meaning many and Greek karpos or Latin carpa meaning fruit referring to the abundant fruit production on the plant.
Prickly Paddymelon. Prickly refers to the soft spines on the fruit. Paddy is of uncertain origin, and is locally attributed to 'Paddy' the typical Irishman who grew them believing they were edible.

Other names:

Gooseberry cucumber
Paddy Melon

Summary:

A prostrate, running, annual herb or vine (to 4 metres) with slender rough stems. It has golf ball size striped, softly prickly melons arsing from yellow, 5 lobed flowers in summer. The green leaves, stems and fruit have a bitter taste and a strong smell when crushed.

Description:

Cotyledons:

Two. Oval. Tip notched. Sides convex. Base tapered. Hairless. Short stalk.

First leaves:

Oval to spade shaped, slightly lobed, edges toothed. Tip round. Notched where petiole joins blade. Hairy on edges and underneath.

Leaves:

Alternate. Dark green to yellowish green. Simple undivided tendril below each leaf.
Petiole - Rough, stout and hairy and about the same length as the leaf blade, 10-80 mm long.
Blade - Egg-shaped 25-75 mm long by 25-80 mm wide. Prominent veins. Notched where petiole joins leaf. 5 rounded, wavy, toothed lobes with the central one longer than the others. Central lobed may be divided again into 3 lobes. Central lobe has a short sharp flexible point. Almost hairless on top but rough with hairs from warts underneath.

Stems:

Green to yellowish green, slender, rough and prickly, vine up to 2000 mm. Branch near centre of plant. Pliable when young, brittle when old. Sometimes form extensive mats.

Flowers:

Yellow to cream male and female flowers sometimes striped with green. Male flowers have yellow stamens in the centre, females don't. May be all male or all female plants or both may be on the same plant. Male flowers are on slender stalks (peduncle to 5 mm long, pedicel 3-8 mm long) in clusters of 2-4 in the leaf axils. Female flowers are single or a pair on stalks (pedicels) 3-8 mm long. Floral tube 3 mm long.
Ovary - Oval, bristly, 2-3 mm long, usually 3 celled with many horizontal ovules. Receptacle hairy, 3 mm long.
Sepals - 1.5 mm long, lobes tapering to a fine lip.
Petals - Yellow to cream, 4-5 mm long by 6-15 mm wide with 5, egg-shaped, lobes.
Stamens - 3, free.
Anthers - Parallel sided, curved, deeply indented. Appendage at the top is shorter than the anther.

Fruit:

Globular 20-30 mm diameter. Covered with long, soft, often hooked bristles. 5 lengthwise light and dark stripes, or mottles. Dark green initially and yellow on maturity. Flesh yellow-green and bitter. Borne on a slender curved stalk.

Seeds:

Many, pale yellow, oblong to egg shaped, flattened, 3-4 mm long. Surface hairless.

Roots:

Slender taproot with many, strong, shallow laterals.

Key Characters:

Spined fruit slightly smaller than a golf ball. Strong smell when crushed.

Biology:

Life cycle:

Annual. Germinates in spring and summer, often after summer rain, and grows rapidly to over 2 m in diameter. It flowers in summer to autumn.

Physiology:

Fruit acts as an emetic.

Reproduction:

By seed.

Flowering times:

November to March in SA.
Summer to autumn in NSW.
January to February in Perth.
Summer to autumn in WA.

Seed Biology and Germination:

Vegetative Propagules:

None.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Dry melons are spread readily by running water.
Cultivating machinery spreads seeds by dragging vines.
Birds also spread seed.

Origin and History:

South or eastern Africa.

Distribution:

ACT, NSW, NT, QLD, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Arid to semi arid.
Often abundant after summer rains.

Soil:

Common on sandy, alluvial, clay and loam soils and gilgai depressions or flats that are occasionally flooded.

Plant Associations:

Prefers bare disturbed areas with summer moisture.

Significance:

Beneficial:

Honey plant producing nectar.
May reduce erosion on sandy denuded soils.

Detrimental:

Weed of fallows, stubbles, pastures, roadsides, summer moist areas, firebreaks, water courses, stock yards and summer crops.
Vines interfere with cultivation of the following winter crop.

Toxicity:

Horse, sheep and cattle losses have been associated with eating the melons. The smell of the plant makes it generally unpalatable and stock problems are not common. Most problems occur when feed is scarce.
Implicated in blindness in horses in NSW.
Feeding tests with sheep have not resulted in poisoning.
One case of child poisoning after eating melons and one case of adult poisoning after receiving an enema made from a decoction of it are reported in Everist (1974).

Symptoms:

Horses: Blindness, deafness, hind limb weakness.
Sheep: Shortness of breath, depression, scouring.
Pigs: Drunken staggering, scouring.
Others: Diarrhoea, vomiting, depression and death.

Treatment:

Remove stock from infested areas.
Don't allow children to play with melons.

Legislation:

Noxious weed of WA. (Pest plant in the Murray shire.)

Management and Control:

Prevention of seed set by mechanical removal is feasible on small areas. Cultivation is effective but may lead to erosion problems. Herbicides are effective but need to be applied when the plants are young and not suffering water stress. Heavy grazing with wethers provides good control if feed is available to avoid problems with toxicity. This may be assisted by applying low rates of hormone herbicide to make the melons more palatable. Multiple germinations may occur over summer requiring repeated control measures. The use of residual herbicides such as Atrazine plus spray oil helps control subsequent germinations but may restrict the types or times of sowing of following crops. Triclopyr, metsulfuron and 2,4-D are commonly used for control.

Thresholds:

Eradication strategies:

Herbicide resistance:

Relatively tolerant to glyphosate.

Biological Control:

Grazing with 24 wethers/ha for 2 weeks on a supplement of 150 g/head/day of Lupins or equivalent provides reasonable control of vegetative plants.
Biocontrol agents are unlikely to be introduced because of the number of closely related economic crops.

Related plants:

West Indian Gherkin (Cucumis anguria)
Ulcardo Melon (Cucumis melo ssp. agrestis)
Rock Melon (Cucumis melo ssp. melo)
Horned Cucumber (Cucumis metuliferus)
Water Melons, Pie Melons (Cucumis myriocarpus)
Cucumber (Cucumis sativus)

Plants of similar appearance:

Camel Melon is easily distinguished by its large fruit, branched tendrils and larger leaves that are usually a lighter green with more lobes and often with lighter coloured veins. In the cotyledon stage Camel Melon has a more obviously veined cotyledons than Prickly Paddymelon.

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P159. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P807. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P341. Diagram.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P625.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P220-222. Diagram.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P186-187. Diagram.

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). #379.5.

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). P159. Diagram.

McBarron, E.J. (1983). Poisonous plants. (Inkata Press, Melbourne). P41. Diagram.

Meadly, G.R.W. (1965). Weeds of Western Australia. (Department of Agriculture - Western Australia). P136-138. Diagram. Photo.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P409-410. Photos.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P102. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.