name1         name2 seed
      Acer   platanoides 32.0
    Lamium         album 12.0
     Ajuga       reptans  4.0
 Chamerion angustifolium  1.5
    Conyza     bilbaoana  0.5
  Brassica         napus  7.0
      Acer      palmatum 21.0
    Conyza   sumatrensis  0.6