Shepherd's purse seedheads

Plant families: Brassicaceae

Find out about the Brassicaceae or mustard family, which includes honesty, sweet rocket and wallflower.

The mustard family, Brassicaceae, is one of our most well-known plant families, owing to the edible crops, or brassicas, we love to grow to eat. These include cabbages, cauliflower, broccoli and kale, as well as radish and turnip. But did you know there were many ornamental plants in this family, too?

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Most plants in the Brassicaceae family are herbaceous plants, but there are a few shrubs. Typically, they have cross-shaped, or cruciform, flowers with four petals and two long and two short stamens. These develop into pod-like fruits called a silique, which eventually partially disintegrate, leaving the seeds held in a translucent case. Most Brassicaceae seed pods are oblong, as with radish and rocket, but some are disc-shaped, like honesty.

Like their cabbage and broccoli cousins, all brassicas prefer alkaline soils and are susceptible to club root.

Another way to identify plants in the Brassicaceae family is by crushing the leaves and smelling them, they all have a distinct and familiar ‘mustard-like’ smell. Like their cabbage and broccoli cousins, all brassicas prefer alkaline soils and are susceptible to the disease club root.

Here are some popular members of the Brassicaceae family.

Candytuft, Iberis sempervirens

Candytuft is a cheery annual, often used to fill gaps in the border or in container displays. It bears summer flowers in pink, purple and white, which are very attractive to hoverflies. Grow in moist but well-drained soil in full sun to partial shade.

Height x Spread 20 x 30cm

White-flowering candytuft flowers
Candytuft, Iberis sempervirens

Honesty, Lunaria annua

Honesty is best known for its translucent, papery seed cases rather than its white or purple flowers. Biennial, it develops a large taproot and doesn’t like being moved – if sowing in pots make sure you plant out before the root gets too big. Grow in moist, alkaline soil in sun or partial shade.

H x S 90 x 30cm

Purple honesty flowers and seedheads
Honesty, Lunaria annua

Sweet rocket, Hesperis matronalis

Sweet rocket bears clusters of fragrant, pale lilac flowers from late spring to early summer, which fill the air with scent in the evening. Grow in moist soil, in sun or partial shade. Deadhead regularly to prolong flowering but allow some seeds to develop as it readily self seeds.

H x S 90 x 50cm

Sweet rocket flowers
Sweet rocket, Hesperis matronalis

Sea kale, Crambe maritima

Sea kale is known by a variety of names, including scurvy grass. Traditionally it was pickled to be eaten for long sea voyages and used to prevent scurvy. Its roots, leaves and fragrant flowers are edible, but these days it’s also grown for its ornamental value. Grow from thongs (root cuttings) in moist but well-drained soil.

H x S 75 x 60cm

Sea kale growing with thrift
Sea kale, Crambe maritima, growing with thrift, Armeria maritima

Night-scented stock, Matthiola longipetala

Night-scented stock bears wonderfully fragrant flowers, which open in the evening. Grow it close to the house or near a bench or window, where you can appreciate its scent. The flowers are edible and may be candied, for decorating cakes.

H x S 40 x 30cm

Night-scented stock flowers
Night-scented stock, Matthiola longipetala

Wallflower, Erysimum

Wallflowers can be biennial or perennial. Biennials bear tight clusters of fragrant yellow, orange-red, dark red, or brown flowers in early spring, while perennial wallflowers, such as Erysimum ‘Bowels’s Mauve’ bloom over a long period, but have little or no fragrance.

H x S 30 x 40cm

Wallflower, Erysimum cheiri flowers
Wallflower, Erysimum cheiri

Pak choi, Brassica rapa

Pak choi is a leafy crop, bearing leaves that can be used in salads or stir fries. Best grown in partial shade and moist soil to avoid bolting. Harvest young leaves on a cut-and-come-again basis to add colour to salads, or use mature heads in stir fries.

H x S 20 x 10cm

Shepherd’s purse, Capsella bursa-pastoris

Most commonly regarded as a weed, shepherd’s purse is named after its triangular, or heart-shaped flat seed pods, which resemble a purse. It’s a small annual with pretty white flowers in spring. It bears masses of seed in summer.

H x S 30 x 20cm

Shepherd's purse seedheads
Shepherd’s purse, Capsella bursa-pastoris

Sweet alyssum, Alyssum maritimum

This hardy annual will quickly fill gaps in borders, bearing masses of snow-white flowers all summer long. Low-growing, sweet alyssum is perfect for rock gardens or low maintenance container displays, and can even be planted in walls and baskets where its flowers can cascade down in great clouds.

H x S 10 x 25cm

White sweet alyssum flowers
Sweet alyssum, Alyssum maritimum

Woad, Isatis tinctoria

Dyer’s woad is a tall brassica bearing masses of bright yellow blooms on sturdy stems. It was traditionally used as a clothes dye – its leaves were harvested and soaked in water to produce a blue dye, which could be dried and used as a face paint and to colour wool and textiles. Today it makes a good wildlife plant but it’s also possible to grow and harvest your own dye.

H x S 100 x 50cm

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Woad flowers
Woad, Isatis tinctoria

More Brassicaceae plants to try

Basket-of-gold, Aurinia saxatilis
Charlock, Sinapis arvensis
Rose of Jericho, Anastatica hierochuntica
Watercress, Nasturtium officinale
Bok choy, Brassica rapa var. chinensis
Cauliflower, Brassica oleracea var. botrytis
Kohlrabi, Brassica oleracea var. gongylodes

Watercress leaves
Watercress, Nasturtium officinale