Low-head hydropower involves dams on rivers.

I think that the Low-head hydropower involves small dams on minor rivers. 
Low head hydropower plants are those that operate with a water level difference of 30 feet or less. The systems that generate electricity involve diverting water from a river that is delivered to a power house containing a turbine, generator or other equipment that convert mechanical energy to electrical energy.

Telophase colchicine is a chemical obtained from plants that prevents the assembly of spindle fibers