242 BIOLOGICAL PROBLEMS 



A century ago the only species of Spartina known 

 in Europe was S. stricta^ a low -growing species 

 common on mud flats from Devon to Lincoln and 

 on the Continent. In 1836 this was joined by a 

 second species, S. alterniflora, supposed to have been 

 introduced accidentally by shipping from America. 

 Its occurrence in Southampton Water and at one 

 other spot, the mouth of the River Adour, at the 

 southern end of the Bay of Biscay, was well known 

 to botanical geographers in the middle of last century. 1 

 In 1870 a third species, S. Townsendii, the subject of 

 this notice, was found also in Southampton Water, 

 and it is this form which has spread in recent years 

 in the marvellous manner just indicated. 



There is no reason for believing S. Townsendii to 

 be an introduced form, for it is not known to occur 

 anywhere else in the world. The current hypothesis, 

 due to Dr. O. Stapf, is that it originated in situ as a 

 naturally produced hybrid between the two other 

 species (S. stricta and S. alterniflora) already on the 

 ground, a hypothesis which gains weight from the 

 fact that in the Adour River locality the only other 

 spot where these two species occur together a fourth 

 form (S. Neyrautii), having much in common with 

 S. Townsendii, has made its appearance. The pre- 

 sumption is that both these new forms are natural 

 hybrids, but the matter requires corroboration at the 

 hands of some competent breeder. 



It is probably safe to estimate the present area 

 occupied by S. Townsendii at 20 square miles, an 

 area which is continually extending. The ground it 

 covers is soft mud stretching down from high-water 

 mark some 4 feet vertical. The grass is exposed as 

 the tide runs off, and is accessible for cutting in the 

 ordinary way. It reaches its full growth in the late 



1 A. De Candolle, Gtographie Botaniqne, 1855, p. 1053. 



