The Pea family (Leguminosae) is now divided into 6 sub-families of which Papilionoidea is the most important. It includes False Acacia, Gorse, Broom, Laburnum, Wisteria, Judas Tree, Peas (Pisum), Beans (Phaseolus), Soya bean, Lentils, Clover, Lucerne, Sweet Pea (Lathyrus), Lupins and many wild flowers. The Pea flower, with 5 petals arranged in a ‘boat’ shape, is characteristic of this family. The word Legume, from the Latin legumen for ‘pulse’, refers to the fruit of the family which is usually a legume (pod) that splits on 2 sides to release its seeds
Basic Flower Parts – 5 Sepals, 5 petals, 10 Stamens, 1 Carpel. Superior Ovary, Nectaries. Fruit is usually a pod or legume.
False Acacia Robinia pseudoacacia, introduced from North America in 1636.
Common Laburnum Laburnum anagyroides, introduced from Europe in 1560, now naturalised.
Lupin, a garden favourite.
The typical flower of this family is the ‘pea-flower’ shown in this photo of an Ornamental Broom. The flower has 5 petals. The upper petal is known as the ‘banner’ (or ‘standard’) and encloses the rest of the petals before the flower opens. This petal swings up when the flower opens to reveal two ‘wing’ petals and two white ‘keel’ petals, which overlap to enclose the reproductive parts. When a bee enters the flower the keel petals are depressed and the stamens and style spring out.
This photo shows a flower before it opens in the background and an open flower in the foreground. The Broom flowers have an explosive mechanism to release pollen. This is triggered when an insect such as a bee depresses the keel petals forcing them apart as it tries to access the nectar at the base of the stamens. The reproductive parts are in a white stamen tube and held in tension against the keel petals. When the keel petals are parted, the tube is released explosively upwards and the stamens and style curve round as shown in these photos.