The number of seeds produced by a ragwort plant is often stated as being 150,000 and this is then built up to make out that this make the plant a risk for spreading everywhere.
This figure is actually at the top end of the plant's production. Many plants produce far less than this. In fact this figure is really hard to justify.
The best reference work on Ragwort Ecology is perhaps that published by John L Harper and W.A Wood in the July 1957 edition of the Journal of Ecology. It publishes two sets of survey figures.
The first gives total seed per plant figures at 8 sites as
120,400 and finally reaches the highest figure of 174,230 with plants that have been cut down and prevented from flowering in their second year which produce more seed in the 3rd. A rather exceptional occurrence in nature.
The second set of data concerns a separate survey that produced figures for individual florets on a plant. Since each floret can produce a seed these figures should be approximately the same. ( Ragwort produces an array of small yellow daisy-like flowers each of which is called a "capitulum" which is the Latin for "little head". Each of the capitula contains many tiny florets each of which can make an individual seed.)
This floret survey gives figures of
These are nothing like 150,000. And that is by no means the most exaggerated figure that is publicised.
A leaflet from a horsey charity making the claim of each plant producing 150,000 seeds was banned by the Advertising Standards Authority.
During the discussion in the House of Lords of the Bill that became the Ragwort Control Act
Baroness Masham of Ilton said the following.
"I am told that each plant can produce between 150,000 and 250,000 seeds that, once airborne, can travel up to 10 miles."
The seeds only normally move a matter of metres See ragwort- how far do the seeds disperse. The figures for seed production are clearly exaggerations. This is only one of a number of misleading things said by the Baroness during a debate in the House of Lords. See Baroness Masham's many errors on ragwort.
This page is part of the Common misleading statements about Ragwort section