Bushy Sennas
What are they?
The word 'senna' is used for a variety of plants - usually with yellow flowers - in the pea family. Some are perennial and develop woody stems and usually shrubby growth and those are the species that are covered here. The original 'senna pods' were not tablets, but the pods from certain species of senna and a number of such plants have laxative qualities if eaten!
Where are they found?
There are no native species in this group and a number of them originate in warmer, even tropical climates. They often have showy flowers and unusual seed pods, making them of interest to gardeners, so plants in this group are most likely to be found as garden escapes in urban areas.
Identification
These bushy species can readily be identified by a combination of their pea-type flowers and details of the seed pods.
Common Bladder-senna Colutea arborescens
Introduced from southern Europe. Occasionally self-seeds from garden plantings into neighbouring land. More or less established in a few places on rough ground in urban areas. Flowers May to July. A many-stemmed, suckering shrub to about two metres in height with pale, peeling bark. The seed pods expand like small bladders as they develop and often become reddish in colour.
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Orange Bladder-senna Colutea x media
(Colutea arborescens x C. orientalis) A hybrid of horticultural origin, recorded as escapes from cultivation in Cambridgeshire. Differs from Common Bladder-senna in its coppery orange flowers.
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Scorpion Senna Hippocrepis emerus
Introduced from southern Europe. Occasionally grown as a garden plant and once found on a road verge in East Suffolk. Flowers May to July. A many-stemmed, open shrub to about 1.5 metres. The bean-like seed pods are segmented and have a distinct 'scorpion tail' at their tip.
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