Seasonal Wild Flowers

Latin name

Gunnera tinctoria

Family

Gunneraceae

Flowering season

June to August

English distribution

It is cultivated in gardens and estates throughout the

country.

Naturalised escapes are found predominantly in the

Southwest

They are thinly scattered elsewhere.

See the BSBI distribution map for Giant-rhubarb

Habitat

It is a neophyte, which was introduced in the late

1840s and first seen in the wild in the early 1900s.

Garden escapes, either self-sown or garden throw-outs,

have become naturalised, by fresh waters, in damp

grassland, damp woodland and on sea-cliffs.

It is on the increase.

Description

Giant-rhubarb is a non-native, large-leaved, robust,

rhizomatous, thicket-forming, invasive herb growing up

to 2.5m.

In my experience male and female flowers are on

separate broad stems of  up to 1m, but floras state that

the flowers can be bisexual.

Male flowers appear first and are in clusters. Each has

2 stamens.

Female flowers have 2 white styles.

The fruits are orange drupes, each containing one seed. 

Each plant can produce up to 250,000 long-lived, seeds

a year.

The leaves are green, palmate and up to 2m across.

Leaf stems are up to 1.5m and have pale, rigid, prickles.

Giant-rhubarb is strikingly large but can be invasive

in the wild.