246 THE JOURNAL OP BOTANY 



hybrid between the same two parents in another part of the world 

 and its extreme similarity to Townsend's grass. As to structural 

 characters, there is no doubt that many of them may be 

 considered as intermediate between those of S. alterniflora and 

 S. stricta, although they are frequently, more or less, obscured by 

 the remarkable readiness with which Townsend's Spartina 

 I'esponds to external conditions, now dwarfing down to the 

 modest size of S. stricta, now running up to and even exceeding 

 the height of fine examples of S. alterniflora. Similarly, its 

 remarkable vigour, its pronounced instability, and its varying 

 fertility, very much enhanced in certain years and almost 

 suppressed in others, may be adduced in favour of the hybrid 

 nature of the grass, as those conditions are traits frequently 

 observed in hybrids. But the strongest evidence seems to be in 

 the following fact : — Spartina alterniflora and S. stricta meet out- 

 side their English area only in one other place, namely, the 

 estuary of the Bidassoa River, south of Bayonne, in the Bay of 

 Biscay. There they grow intermixed, and among them has been 

 found their hybrid. Foucaud described it in 1895, and named it 

 Spartina Neyrautii, after its discoverer, Neyraut. Now this 

 S. Neyrautii is so similar to S. Toivnsendii that Foucaud pro- 

 claimed both as hybrids from the same parents, explaining such 

 differences as there are by the assumption that S. alterniflora was 

 the female parent in the case of the Bidassoa cross, and S. stricta 

 in that of the English plant. The fact is very remarkable, and 

 the argument deducible from it for the hybrid origin of Towns- 

 end's grass has almost the force of experimental proof. 



Thanks to its vigour and occasional fertility, Townsend's grass 

 has, in a comparatively short time, conquered thousands of acres 

 of bare mud-land, it has invaded and, in places, much reduced 

 the beds of Spartina alterniflora in Southampton Water, and even 

 attacked the marshes which so far have been the home of 

 Spartina stricta. However, its principal domain is and will 

 probably for ever be the mudflats from one to three feet below 

 high water-mark. Here the changes brought about by Towns- 

 end's grass are remarkable. It is not only that the aspect of the 

 flats is altered, the eye meeting great expanses of green com- 

 parable to meadows or cornfields, where there was previously a 

 monotonous sheet of grey at low- and half-tide, also the animal 

 life on the flats and their physical character is undergoing a 

 change. To mention only a few economically interesting effects 

 on the fauna : in more than one place the larger molluscs which 

 were collected for food have disappeared ; with the arrival of the 

 grass, eel-spearing has been seriously interfered wath, whilst even 

 duck shooting has been spoiled owing to the birds finding a 

 welcome cover in the dense grass belts. But the most important 

 change concerns the physical condition of the flats. It is obvious 

 that the copious systems of roots and stolons must contribute to 

 the stabilisation and solidification of the mud. In addition to 

 this binding action the stems and lower leaves and leaf-bases act 

 as a very effective strainer on the water, which is charged with 



