Bladderworts

While we were staying on Skye I was on the lookout for Bladderworts, as Fred and I have been trying to sort out the different British species.

The Bladderworts (Utricularia) are aquatic carnivorous plants which have small bladders in which they trap microscopic animals.

There are 6 British species, but most of them are impossible to identify accurately without microscopic examination unless they are flowering. Only Utricularia minor flowers freely in Scotland.

This picture shows Utricularia stygia growing on the margin of a loch on Skye.

From the loch there was an excellent view to the Cuillins.

The commonest species on Skye was Utricularia minor, but I did not find any in flower. The following pictures were taken in Glen Coe on our way home.

The small pool where it was growing was surrounded by a bog and, as you can see, it was raining.

Most of the flowers were in the middle of the pool, but this one was near enough to the edge for me to get a close-up.

Under the microscope, it is possible to see the structure of the hairs surrounding the mouth of one of the bladders.

An introduced Utricularia species, possibly U. macrorhiza, grows close to our home, and this photo taken under the microscope shows the bristles on the sides of the leaves, which are also present on Utricularia stygia. In the picture above, you can see that Utricularia minor has no such bristles.

The most reliable way of separating the species is by microscopical examination of what are known as quadrifid hairs, which are inside the back of the bladders. We have used a stain to show these more clearly.

The first picture shows U. stygia, in which the hairs form an X.

In U. minor, the shorter pair of hairs hang down almost alongside the longer pair.

In the introduced Utricularia, the shorter pair have an angle of almost 180 degrees.

For more pictures of bladderworts, see the Bladderwort page on our site.