Friday, 19 October 2012

Water Fern (Azolla filiculoides)


      Knowing when to stop is a problem confronting a lot of situations in both human and plant life. In my case it was with do-it-yourself: my wife and I had a system; she would think up jobs and I'd do them. Usually with the accent on 'do'. On one occasion, some lino needed laying in the bathroom. We had not been in the house long, having got a mortgage at the extreme end of what we could afford. It was at that time in the '80's when the chancellor was putting up the interest rate three times before breakfast and we could only just afford to eat. The lino therefore was a luxury and I was under great pressure not to cock it up.

      With great concentration, I made a plan of the bathroom and measured the positions of the bath, toilet, sink, etc, then drew their outline on the lino before cutting out the shapes. The measurements were exact, however the fact that I drew them on the back of the lino ( I didn't want to mark the pattern) meant that, when it was rolled into position, the bath was on the left hand side of the room, the lavatory and wash-basin were also on the left but all the cut-outs were on the other side. This left me with the options of either throwing myself out of the window before my wife found out, or to piece it together. As the extension roof was just below the window, it seemed likely I'd go through that and simply end up doing more repairs, so I 'invisibly' patched the lino. I thought the jig-saw puzzle effect was quite original. Unfortunately, my wife didn't.

Water Fern

      Water fern (Azolla filiculoides) is one of many plants which, like me, don't know when to stop. Each tiny plant breaks into smaller sections, replicating itself at a prodigious rate, so that large surface areas quickly become covered. This was so extreme in the pond at Fletcher Moss Gardens where I worked, that one old chap, thinking it was a lawn, tried walking across it. Unfortunately, Jesus he was not, and only his hat indicated the route of his submerged wanderings. The fact that the water fern cuts out light means that oxygenating plants growing below are unable to photosynthesise, so they die and the general health of the water suffers. However, a positive aspect lies in the fact that it is able to 'fix' nitrogen, a valuable plant nutrient, from the atmosphere. As a result of this, it is grown in rice paddies to enhance growth of the crop. Equally, it can be removed from your pond and used as an effective green manure when incorporated into beds.

Pond at Capel Manor Gardens

Coot finding it hard work


As the days grow colder, the plant takes on an attractive purple colour for a number of weeks, before producing buds which drop to the bottom and overwinter away from ice. Originating in North and South America, it causes problems in Australia, New Zealand and various other countries. It is not to be confused with our native common duckweed (Lemna minor), which has a similar carpeting effect on water. According to Richard Mabey in Flore Britannica, this used to be known as Jenny Greenteeth, 'an amorphous monster that would suck children into the depths if they wandered too close'. The story was probably used to keep youngsters away from dangerous water.


      Being aware of a plant's propensity for spreading is important and it is well worth checking before subjecting yourself to another problem which 'seemed a good idea at the time'.

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