Nasturtium

Tropaeolum majus L.

Synonyms -

Family: Tropaeolaceae

Names:

Tropaeolum is Greek meaning a trophy and refers to the trunk of a tree where the helmets and shields of the defeated were placed.
Majus is Latin for large and probably refers to the flowers.

Other Names:

Garden Nasturtium.

Summary:

Nasturtium is a soft, sprawling or scrambling herb with somewhat fleshy stems. The leaves are circular, 30-80 mm diameter and their stalk is attached to the centre of the leaf, like a tiny umbrella. The large trumpet-shaped flowers vary in colour from yellow through orange to red and have a prominent straight or curved basal spur. There are 8 stamens and a slender 3-lobed style. The fruit splits into 3 segments.
Native to South America, Nasturtium is a garden escape of hybrid origin and now a weed of roadsides, waste land and disturbed creek lines. It flowers mainly in spring.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Spirally arranged and umbrella like (peltate) with radiating veins. The young leaves have a peppery watercress flavour.
Stipules - Present.
Petiole - 50-200(300) mm long.
Blade - Circular to kidney shaped, 35-80(150) mm diameter. Entire to having deeply wavy edges. 7-10 veins radiate from the central stalk (petiole). Hairless, but the under surface is rough with small warts (papillose) and bluish.

Stems:

Weak, soft, somewhat fleshy and scrambling or climbing to usually about 1 m long and occasionally up to 10 m long. Circular in cross section, 4-8 mm diameter and single or branching from the base. They have watery sap and are usually hairless.

Flower head:

Single to clusters of 3 flowers on stalks (peduncles), 30-120(250) mm long arising from the leaf axils.

Flowers:

Large, trumpet-shaped, 25-70 mm diameter, creamy white to yellow through orange to red and have a prominent straight or curved basal spur. Zygomorphic, bisexual. Pleasant aroma. Peppery watercress flavour.
Ovary - Superior. 3 fused carpels. 3 locular with 1 ovule per loculus.
Style - slender.
Stigmas - 3, terminal.
Calyx - 5 free, overlapping sepals, 10-20 mm long with one forming into a nectar bearing spur that is 20-35 mm long and straight or curved.
Petals - 5, free, overlapping, clawed, mostly rounded, sometimes toothed, 25-35 mm long. Lower 3 broader than the upper 2. Lower ones deeply fringed on the claw. Upper 2 inserted into the opening of the spur. Occasionally there are semi double varieties with 7 or 8 petals.
Stamens - 8 in 2 rings of 4. Unequal. Filaments thread like and free.
Anthers - 2 celled, small, attached at the base, laterally dehiscing by longitudinal slits.

Fruit:

3 by 1 seeded nut like fruits with 2 flat faces and the third rounded and bluntly ribbed. Non splitting (indehiscent). About 10 mm long. Green and succulent until they drop and turn light brown.

Seeds:

Brown, ribbed, globular, 5-7 mm diameter, hairless, solid creamy-white centre (endosperm).

Roots:

Taproot.

Key Characters:

Leave peltate.
Uppermost sepal spurred.
Flowers zygomorphic.
Petals free.
Ovary superior.
8 stamens in 2 whorls.
Staminodes absent.
3 carpels.
Adapted from G. Harden and E.M. Bennett

Biology:

Life cycle:

Annual to biennial.

Physiology:

Reproduction:

By seed.

Flowering times:

Mainly August to November in Perth.
Most of the year in WA.
Spring to autumn in NSW.
October to May in NZ.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Most long distance dispersal is by intentional planting. Medium distance dispersal is usually by dumping of garden refuse. Short distance dispersal is by seed.

Origin and History:

South America.
Nasturtium is a hybrid from species that are native to Bolivia and Columbia.

Distribution:

NSW, QLD, SA, VIC, WA.
Lord Howe Island.
Jarrah forest, Swan coastal plain and Warren regions in WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Disturbed areas, hedges, roadsides, moist shady areas.

Climate:

Temperate areas.

Soil:

Sands.

Plant Associations:

Significance:

Beneficial:

The leaves and flowers used as a salad and soup vegetable or cress substitute and table ornament. Pickled unripe seeds are used as a substitute for capers. It is cultivated as an ornamental flowering plant.

Detrimental:

It is a minor environmental weed of disturbed areas, hedges, roadsides and moist shady areas.

Toxicity:

Not reported as toxic.

Symptoms:

Treatment:

Legislation:

None.

Management and Control:

Thresholds:

It rarely invades agricultural situations or crops.

Eradication strategies:

Avoid dumping garden refuse containing Nasturtium in areas where it may establish.
Manually remove, ensuring the larger roots are also collected, and burn. There is often a large germination of seedlings following removal of the parent plants. These can be controlled by light cultivation or by the herbicides below.
2,4-DB at 4 L/ha plus 0.25% wetting agent or 80 mL 2,4-DB(400g/L) plus 25 mL wetting agent in 10 L water will provide reasonably selective control in bushland situations. In areas where hormone herbicides can't be used, apply 20 mL glyphosate(450g/L) plus 25 mL wetting agent in 10 L water. Apply any time the plants are actively growing. Seedlings can be controlled with half of these rates. Repeat as necessary.

Herbicide resistance:

None reported.

Biological Control:

None

Related plants:

None naturalised in Australia.
Chilean Flame Pepper (Tropaeolum speciosum) is a climber with 5-fingered leaves and smaller scarlet flowers about 15 mm diameter.

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P232.

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

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

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume 3. P31-32. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (2007). Western Weeds. A guide to the weeds of Western Australia. (Second Edition). Plant Protection Society of Western Australia, Perth, Western Australia. P248.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #1022.1.

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). P501.

Moore, J.H. and Wheeler, J.R. (2008). Southern Weeds and their Control. (Second Edition). Department of Agriculture and Food Western Australia. P134. Photos.

Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P565.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Roy, B., Popay, I., Champion, P., James, T. and Rahman, A. (1998). An Illustrated Guide to Common Weeds of New Zealand. (New Zealand Plant Protection Society). P295. Photo

Stucky, J.M. (1981). Identifying Seedling and Mature Weeds Common in the Southeastern United States. (The North Carolina Agricultural Research Service and The North Carolina Agricultural Extension Service, North Carolina State University, Raleigh).

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 for more information.