Crassula helmsii (T. Kirk) cockayne: is it an aggressive alien aquatic plant in Britain?

  • Published source details Dawson F.H. & Warman E.A. (1987) Crassula helmsii (T. Kirk) cockayne: is it an aggressive alien aquatic plant in Britain?. Biological Conservation, 42, 247-272.


This study is summarised as evidence for the following.

Action Category

Crassula helmsii: Use lightproof barriers to control plants

Action Link
Control of Freshwater Invasive Species
  1. Crassula helmsii: Use lightproof barriers to control plants

    A before-and-after study at a single lake in Dorset, UK (Dawson & Warman 1987) found that covering C. helmsii with dark material killed the plant, although it slowly recolonized, and no statistical tests were carried out. Two months after the dark sheeting was applied, the underlying C. helmsii was killed. However, after this the plant progressively recolonized the site. Typar geotextile sheeting was used to cover 50 m2 of C. helmsii. No control or comparison, and few details of the experiment (e.g. timing, water depth), were provided.

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