Flora of Northern Ireland

Canals

Canal with duckweed and marginal floraAlthough nearly all are now disused, canals remain a significant feature of parts of lowland Northern Ireland. They are an important habitat for wild plant biodiversity, and several extremely rare species occur in some of them. Much of the aquatic and canal-side vegetation is similar to those found in ponds, lakes and slow rivers. The aquatics are of two sorts: completely submerged, and emergent (i.e. with parts both below the water surface and rising above it into the air).

The Lagan Canal connected Lough Neagh at Ellis's Cut with Belfast Lough. Between Ellis's Cut and Lisburn it is an entirely artificial cut, but between there and Belfast it made use of the River Lagan, with some artificial cut-offs to by-pass unnavigable stretches of river. The Coalisland Canal connected that town with the Blackwater and thereby Lough Neagh. The Newry Canal connected Lough Neagh with Newry town and docks. All these canals which connect into Lough Neagh probably allowed the dispersal of a number of plant species into and out of the Lough Neagh basin, such as Flowering Rush (Butomus umbellatus), Sweet Flag (Acorus calamus), Greater Yellow-cress (Rorippa amphibia) and Greater Duckweed (Spirodela polyrrhiza).

The Ulster Canal connected the Blackwater with River Erne. Much of it is now virtually dry and is therefore probably the least valuable botanically.

The Lower Bann is the only river which drains Lough Neagh. It remains navigable between the Lough and the sea, and short stretches of artificial cuts accommodate locks by which boats can descend to sea level.

In addition to navigable canals, there is a significant number of artificial drainage cuts engineered to drain agricultural land (like the Navvies' Drain and the Tunny Cut which both connect Portmore Lough with Lough Neagh) Their vegetation is similar to those of canals and slow streams.

Significant or characteristic species of canals (see under riverside vegetation for species characteristic of canal banks)

Emergent and floating-leaved aquatics Totally submerged aquatics
Acorus calamus Elatine hydropiper
Alisma lanceolatum Elodea canadensis
Alisma plantago-aquatica Elodea nuttallii
Baldellia ranunculoides Lagarosiphon major
Butomus umbellatus Lemna trisulca
Caltha palustris Potamogeton alpinus
Carex riparia Potamogeton berchtoldii
Equisetum fluviatile Potamogeton crispus
Galium palustre Potamogeton praelongus
Glyceria fluitans Potamogeton x undulatus
Hydrocotyle vulgaris  
Iris pseudacorus  
Lemna gibba  
Lemna minor  
Lythrum salicaria  
Mentha aquatica  
Myosotis laxa  
Myosotis scorpioides  
Nuphar lutea  
Persicaria amphibia  
Phalaris arundinacea  
Potamogeton natans  
Rorippa amphibia  
Rorippa nasturtium-aquticum  
Sagittaria sagittifolia  
Solanum dulcamara  
Sparganium erectum  
Spirodela polyrhiza  
Veronica beccabunga