Identifying Garden Nasturtium (Tropaeolum majus)

Take great care when identifying wild plants and fungi, this blog is not a resource to be taken by itself and further resources will be linked. Consult other sources and double check. While foraging is an extremely rewarding and useful skill, numerous common plants and fungi can make you sick or kill you. Be absolutely sure of what you’re eating and, when gathering, ensure you leave enough not only to ensure the survival and growth of the species but also enough for others to enjoy, from the human and more-than-human communities. Also cultivate an awareness of contamination and pollution – wastewater runoff, spraying, exhaust fumes – as this should affect your decision to harvest.

The Plant

Tropaeolum majus is an annual or shirt-lived perennial “weed” from the Tropaeolaceae family. It is originated in South America but was introduced to other countries, such as New Zealand, as an ornamental flowering shrub. Garden nasturtium has since spread to be more of an invasive plant as it tolerates disturbed soils well such as along riverbanks, roadsides, and in shrubland. Tropaeolum comes from the Latin word meaning “trophy” and was named by Carl Linnaeus because the leaves reminded him of the shields and the flowers of the bloody helmets that would be paraded as a tropaeum in Rome after a battle. Majus just means “larger” due to garden nasturtium’s large flowers. Nasturtium’s received their name due to the fact that they produce an oil similar to that of watercress (Nasturtium officinale) but in fact aren’t closely related to the nasturtium family. The word nasturtium means “nose-tweaker”, which, I assume, refers to the pepperiness of the foliage from garden nasturtiums and it’s namesake family.

Description

Garden nasturtium stems are pale, hairless, and sprawl along the ground, though the leaves and flowers generally stand tall at up to 2m high. Tropaeolum majus leaves are large and nearly circular, 3 to 15cm in diameter and will get larger with age. The leaves are a darker green on top and paler underneath and have a small white dot in the centre with white veins spreading out to the edges of the leaf. Garden nasturtium flowers are medium sized, solitary, and vibrant fiery colours from red to orange to yellow and the colour is often darker at the base of the 5 petals. The flowers contain eight stamens and have a long nectar spur at the bottom of the flower. The seed is similar to a caper and can be used as such. One seed is encased in three pale lobed segments. Nasturtiums will grow from roots and stems and sometimes the seeds will be dispersed by birds and other animals. The leaves, flowers, and stems smell bitter and peppery when crushed.

Ecology

I have come across Tropaeolum majus all over New Zealand, some growing wildly in people’s gardens but most growing along riverbanks, roadsides, and other disturbed sites. Garden nasturtiums prefer lots of sun but do alright in shade, poor soil conditions, and wind. Nasturtiums however aren’t very frost hardy. The flowers bloom over the spring and summer months but the leaves are available to harvest pretty much all year round.

Nutritional & Medicinal Information

All parts of the garden nasturtium are a good source of potassium, phosphorus, calcium, zinc, magnesium, iron, and copper.

The nasturtium essential oil is antimicrobial, antifungal, and anticancer due to it’s high content of vitamin C and polyphenols. This makes it great for using topically on skin conditions as well as using extracts internally for digestive and respiratory issues.

Apparently eating three seeds daily will help build resistance to viruses and eating one leaf every hour when you feel a sore throat coming on can drastically reduce the intensity of the infection.

Possible Lookalikes

Garden nasturtiums are very distinct and easy to identify, I have come across varieties that have white and green speckled leaves which are also edible.

Interesting Facts

Tropaeolum tuberosum is a species in the same family of nasturtium which grows frost hardy edible tubers underground which has been an important food source for people living in the Andes.

Garden nasturtiums repel some “pest” insects but actually trap others, such as the white cabbage butterfly, so it can be useful as a sacrificial plant in your vegetable garden so the unwanted insects lay their eggs on the nasturtiums instead of your annual greens!

Storage & Cooking

Nasturtium is best harvested and eaten fresh, except for the seeds which can be pickled like capers and stored in the fridge for long periods of time.

Nasturtium leaves and flowers provide a delicious pepperiness to salads or stirfries and the large roundness of the leaves made great wraps or baked crisps. Enjoy my fellow foragers!

Further Reading

Weedbusters

Greater Wellington

New Zealand Plant Conservation Network

iNaturalist