Flora of Northern Ireland
Groenlandia densa
© Ralph Forbes
Groenlandia densa
(Map updated: March 2008)
 

Resembling a Potamogeton species, but with opposite, not alternate, leaves. This is a totally-submerged pondweed of base-rich lakes. The only Northern Ireland site is Lough-na-Trosk in Co. Antrim, where it was discovered in 1971. This lake sits in a basin below some basaltic cliffs at about 290 metres altitude and has an alkaline pH.

Two dots appear on the map because the lake falls within two adjacent hectads.

All names: Groenlandia densa (L.) Fourr.; Potamogeton densus L.