Life cycle rules

The spotted knapweed can be classified according to its life cycle stages, which are Seed, Rosette, and Flower.

  1. Seeds can remain viable in the soil for many years, or can become not viable.
  2. Seeds germinate into rosettes.
  3. Rosettes can either remain as rosettes, become flowers, or die.
  4. Flowers can remain flowers, or die.
  5. Flowers produce on average 600 seeds per year, of which 72% are viable.

We need probabilities associated with the events given in 1-4. These can be found by collecting field data. Here, we made use of completed spotted knapweed studies to determine these values. They are given in the table below.

Seed does not germinate but remains viable0.23
Seed germinates into a rosette0.74
Rosette remains rosette0.52
Rosette bolts into flowers0.35
Flower remains flower0.46