question

Dear Daffnet Users,
 
We all know that most daffodil species and all man-made varieties multiply also through agamic production of bulblets. In this sence one could say that – in adequate conditions – the plant, in its clones, is practically eternal.
What does not seem to be of common knowledge is the life span of a single daffodil bulb. It will be internally renewed from year to year and it will grow in size but what is known about the life expectancy of that single plant? Are there plant, or better daffodil, physiologists who would like to tell what is known in this respect, possibly referred to daffodil types (divisions)?
Thanks to everybody and best regards.
  Henry (Rome)