My tree is very definitely my Colutea, it is not difficult to say and I am not going to call it a Bladder Senna. For a start the common name is inaccurate. It is not a Senna although the leaves are reputed to have a laxative effect similar but milder than senna ( I pass this little snippet on but I have no first hand knowledge of its accuracy and have no inclination towards eating the leaves.) I suppose in addition it is the bladder part of the name I object to. The yellow flowers give rise to paper thin seed pods that are unusual but I find them attractive and an additional attraction of the plant.
I first saw Colutea in Crathes Castle garden, Aberdeenshire, Scotland. I liked it so much I bought a plant from their nursery and brought it over to France. All this without knowing it was called a Bladder Senna.
I love my garden but there is always so much to do that I really appreciate the plants that give back such a lot with so little care. This is where the Colutea fits in so well. The plant covers a wide geographical range in the wild, stretching from the Himalayas to Southern Europe and can survive up to zone 6 0r 7. It is its ability to survive in tough conditions such as a poor dry soil and to withstand strong sun makes it an ideal shrub for difficult spots. It is deciduous and was completely unfazed by the severe period of cold we experienced in February this year.
It produces attractive yellow flowers during the summer. The flowers have a similar shape to pea and bean flowers and is in the same leguminosae family and able to fix nitrogen, it is perhaps this adaptation that allows it to thrive in poorer soils.
The pods start off as a light and translucent and become darker as they mature.
In addition the plant self seeds allowing you to keep back-up plants in the case of disaster or to give to friends. This is my little forest of baby Colutea which have self seeded in the most unhospitable and dry area at the bottom of the garden. I am not sure what I am going to do with them but after they have struggled to go forth and multiply it seems a shame to pull them out and throw them away.
Colutea grows rapidly, which is a good point but it needs to be pruned to prevent it becoming leggy. It can be cut back to in early spring to train it to the shape required, but that is about all the care it requires.
There is a beautiful old specimen in the gardens of the Château de la Roche Courbon not far from here so if it is good enough to be pampered in the garden of a château (despite its unattractive common name!) it is good enough for my little patch .