NUPHAR INTERMEDIA IN BRITAIN 



13 



anther shape in the Avinlochan colony (Fig. 4c) is somewhat elongated compared with 

 normal N. pumila, approaching N. intermedia in this character. It is possible that the 

 Scottish plants with elongated anthers seen by Planchon came from this locality. 



Statistical data for stamen number have not been obtained from all the Nuphar colonies 

 investigated, but the counts that have been made suggest a mean stamen number for 

 N. lutea of c. 105, for N. intermedia of c. 66 and for N. pumila of c. 52. 



(4) Pistils. In the dimensions of the stigmatic disc the size relationships of the 

 three taxa parallel those in sepal and petal length, with N. intermedia again intermediate 

 between N. lutea and N. pumila. The Avinlochan colony is quite anomalous in this 

 character; the mean value given in Table 1 refers to maximum diameter and this is high, 

 owing to a certain amount of ovary fasciation found in many individuals of this colony 

 (Fig. 6e). 



Carpel number is an important diagnostic in Nuphar. The two N. pumila samples, 

 P 1 and P 2, are in close agreement in this character, and the N. intermedia is again inter- 

 mediate between these and the N. lutea aggregate sample. The relationships of the 

 three are shown graphically in Fig. 5. As a result of fasciation in individuals of the 

 Avinlochan sample (see Fig. 6e), the mean carpel number is greater here than in the 

 other two N. pumila samples. The frequency distribution of carpel number in this 

 sample is compared with that in the N. intermedia and N. pumila samples in Fig. 7. 



40 



30 



10 



10 



N. pumila 



N. intermedia 



, N. lutea 



: L._., 



8 9 10 II IZ 13 \^ 15 16 17 18 19 20 21 



Carpel number 



Fig. 5. Frequency histograms of carpel number in British Nuphar taxa. 



Particularly in N. lutea, the stigmatic rays are singularly variable in form. This 

 feature seems to have been overlooked previously by European taxonomists, although 

 in N. America, where the genus is highly polymorphic, Miller and Standley (1912) have 

 emphasized its importance in the diagnoses of some seventeen species. The stigmatic 

 discs illustrated in Fig. 6a-c give some indication of the variability in this character in 

 N. lutea; the individuals from which drawings were made were derived from Tregaron 

 and EUesmere, The rays may be linear and widely spaced, ovate, or so broad as to 



