As a single genus family descriptions of the genus are the same as that of the family.

Australia has 1 naturalised species of Nasturtium – Tropaeolum majus.
Although given species status it is likely to be an old hybrid.

It is an annual prostrate, climbing or trailing plant with stems up to nearly 2 m long.
The almost circular leaf blade has the petiole, up to 30 cm long attached near the centre.
The blade, up to 15 cm across may be lobed.

Flowers, up to 7 cm across are on a stalk or pedicel around 20 cm long.
The calyx has 5 sepals up to 2 cm long and a nectar tube or spur around 3 cm long.
T. majus flowers are red, orange or yellow.

Nasturtium cultivars/hybrids.

The majority of plants seen are hybrids of T. majus, T. minus and T. peltophorum.
Known as Garden Nasturtiums they are often sold as T. majus.

Cultivars can be prostrate, compact and bushy, scrambling, trailing or climbing.
There are dwarfs around 25 cm high and climbers nearly 4 m.
Leaves can be green, blue-green or grey-green and spotted or variegated.

Flowers can be single, semi-double or double with smooth, fringed or lobed petals.

As well as the basic colours of red, yellow and orange they can be burgundy, salmon, rose,
    apricot, pink, cream, violet, purple or a deep almost black red.
There is a huge range of colour combinations and markings.