WeW YORK 

 BOTArsiCAL 



THE 



JOURNAL OF BOTANY 



BRITISH AND FOREIGN. 



POTAMOGETON BENNETTII. 



By Alfred Fryer. 



(Plate .S48.) 



Potamogeton Bennettii mihi. Eootstock with slender stolons. 

 Stem very slender, compressed, ascending, simple at first, afterwards 

 dichotomously branched. Leaves all similar, sessile, linear, narrowed 

 towards the base, margins obscurely serrulate or entire, 3-ribbed, 

 subapiculate or obtuse, alternate, opposite below the peduncles, 

 spreading. Stipules blunt or truncate, scarious. Peduncles slender, 

 equal, exceeding the short ovoid spike. Flowers abortive. Whole 

 plant dark green, drying with a reddish brown tinge. 



Probably a hybrid between P. crisjuis and P. ohtusifolius. This 

 species has usually been passed over by British botanists as a form 

 of P. ohtusifolius, which in early growth it closely resembles. In 

 the flowering state the habit is more like that of P. crispus, although 

 the plant still retains much of the facies of ohtusifolius; or, from the 

 short axillary branchlets, that of Friesii. The faintly serrulate 

 leaves, however, always serve to distinguish P. Bennettii from any 

 of the Graininifolii, this character being constantly present in some 

 of the leaves on every branch; although on others it is either absent 

 or so obscure as to be practically useless. When in flower, the 

 peduncles 6-8 times as long as the spike afford a sufficient distinction. 



When growing, no botanist would be likely to mistake this plant 

 for P. crispus, the species it most closely resembles when carefully 

 examined. The abortive flowers, the narrowly linear often entire 

 leaves, and the numerous axillary branchlets are the safest characters 

 by which the two forms can be separated. 



In Enijlish Botany (ed. 3, vol. ix. p. 44), under P. crispus, Syme 

 wrote : — " The young state of this plant is the P. serrat^is of Hudson ; 

 it is very unlike the ordinary form, and might easily be passed 

 over as P. ohtusifolius, but the leaves are more or less serrulate. A 

 specimen of the ordinary form gathered late in August had thrown 

 out numerous branches of P. serratus from its rootstock, so it can- 

 not be considered as even a variety." In no state of its growth, 

 however, can P. Bennettii be mistaken for the serratus-staie of P. 

 crispus ! The autumnal and winter shoots of the two forms are 



Journal of Botany. — Vol. 33. [Jan. 1895.] b 



