Glyceria canadensis 3 Råby , Vanda Fi 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria declinata 5 Gyllebo, Östra Sönnarslöv Sk 150621 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 3 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 4 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 5 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 6 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 7 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 2 Marknadsbacken, Abborrforsen, Kymmene älv FI 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 3 Marknadsbacken, Abborrforsen, Kymmene älv FI 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 4 Marknadsbacken, Abborrforsen, Kymmene älv FI 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 6 Kongens Bro, Jylland DK 060806 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria nemoralis 1 Manciagire, Lithuania 100714 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria nemoralis 2 Manciagire, Lithuania 100714 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria nemoralis 3 Manciagire, Lithuania 100714 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria nemoralis 4 Manciagire, Lithuania 100714 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 10 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 11 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 12 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 6 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 7 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 8 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 9 near Clarinbridge S of Galway, Ireland 170525 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 1 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 2 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 3 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 4 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 5 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 6 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 7 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 8 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria striata 9 Copenhagen Bot Garden 130604 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 1 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 10 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 11 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 12 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 13 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 2 Råby , Vanda Fi 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 4 Råby , Vanda Fi 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 5 Råby , Vanda Fi 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 6 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 7 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 8 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria canadensis 9 Råby , Vanda FI 120728 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria declinata 1 Benestad Sk 090601 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria declinata 2 Benestad Sk 090601 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria declinata 3 Benestad Sk 090601 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria declinata 4 Benestad Sk 090601 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 1 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 2 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 3 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 4 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 5 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 6 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans 7 Skanörs Ljung Sk 130608 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 1 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria fluitans x notata 2 Södra Paipis, Sibby Fi 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria grandis Frescati, Stockholm 960718 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 1 Marknadsbacken, Abborrforsen, Kymmene älv FI 120729 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 10 Peipsi, Estonia 100709 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 5 Kongens Bro, Jylland DK 060806 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 7 Peipsi, Estonia 100709 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 8 Peipsi, Estonia 100709 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria maxima 9 Peipsi, Estonia 100709 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 1 Bad Gastein, Austria 080704 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 2 Bad Gastein, Austria 080704 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 3 Bad Gastein, Austria 080704 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 4 Bad Gastein, Austria 080704 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).

Glyceria notata 5 Bad Gastein, Austria 080704 - Photo: Jan Thomas Johansson (© 2014 Jan Thomas Johansson).