XXviii. THE FLORA OF HALIFAX. 



B. -Attached Submerged Plants. These are rooted to 

 the bottom of the pond, often in deep water, and grow up to 

 the surface, but hardly rise above it. All the species enumer- 

 ated are in the canal between Halifax and Salterhebble ; the 

 Canadian pond weed and one or two species of Potamogeton are 

 found in the other localities, but the water starwort has a very 

 much wider range as a mud or swamp plant. 



MyviophyUum cilternifloriun , Potamogeton cnspus, 



Callitriche st agnails, P. obtusifolius, 



Elodea canadensis, P. piisillns, 



Zannichellia palustvis, P. pectinatus. 



C. — Attached Floating Plants. Considerable areas of 

 Tag Lock are covered with the floating leaves of Polygonum 

 amphibium and Potamogeton uatans, with their flowering spikes 

 rising above the surface. The arrowhead, Sagittar a sagittifolia, 

 is found in the canal. But the floating grass, Glyccvia fluitans, 

 though it has its place in this group, differs in being more 

 widely diffused, and in being more characteristic of the margin. 



D. — Reed Swamp Plants. Towards the bank, where the 

 depth of water may vary considerably from time to time, occur 

 a number of tall, reed-like, or strap-shaped plants. Their 

 social character is strongly marked, owing to their creeping 

 root-stocks, and from the same cause they fringe the shore, and 

 by retaining the mud, they largely contribute to the silting up 

 of the " pond," and, at the same time, push out further into it. 

 By no means all of them grow together in the same locality : 

 in one dam it may be bur- reed and flag; in another, reedmace 

 and water plantain ; or a fringe of tall grasses along the canal 

 bank ; but each in its turn occupies the position characteristic 

 of the group, the members of which are : 



Iris Pseudacorus, Acorns Calamus, 



Typha latifolia, Alisma Plautago, 



Spavganium vamosum, Phalaris arundiuacca, 



S. simplex, Glyccvia aquatica. 



E. — Marginal Plants. There are several points of 

 interest in connection with all the preceding hydrophytes. 

 The hrst is that, with a few exceptions, they have entered into 

 the flora of the parish only since the making of the canal, as 

 mentioned on p. xv. Nor do they appear to have displaced 

 other water-loving species. The only such that have become 

 extinct are Hippuvis vulgaris and Typha angustifolia. Further, 

 again with one or two exceptions, they are monocotyledons 



