NUPHAR INTERMEDIA IN BRITAIN 



11 



(1) Sepals. The sample data of Table 1 for dimensions of largest sepal show that 

 the two N. pumila samples hardly differ significantly for this character (p — -04). The 

 Avinlochan population evidently has somewhat longer sepals, while in the Chartners 

 population of N. intermedia, the average sepal length is some 25 per cent greater and the 

 average sepal width about 50 per cent greater than in N. pumila. Clearly these figures 

 also indicate a shape difference, which is illustrated in Fig. 2. The sepals of N. lutea 

 are rounded (Fig. 2a), those of N. pumila obovate (Fig. 2d) and those of N. intermedia 

 intermediate in shape as well as in size (Fig. 2b). Characteristically all three possess 

 five sepals. There is, however, some variation in this feature, as can be seen from Table 2. 



Table 2 



Distribution of sepal number in British Nuphar taxa. Percentage representation in each class. 



Taxon 



No. of sepals 



4 



5 



6 



7 



N. pumila (PI + P2) 



3-46 



93-10 



1-72 



1-72 



N. intermedia (Chartners) 





89-18 





10-82 



N. lutea (LI — 12) 





95-73 



4-27 





'-\) 0 0 0 



(a) 



(b) 



Fig. 2. Characteristic sepal shapes in British Nuphar taxa. (a) N. lutea from Ellesmere; (b) N. intermedia 

 from Chartners Lough; (c) " introgressed " N. pumila from Avinlochan and (d) N. pumila from Lochanovie. 



(2) Petals. The size relationship apparent between the three taxa in sepal length 

 holds also in petal length, as may be seen from the data for this character given in Table 1, 

 except that proportionately the petals of N. intermedia exceed those of N. pumila to a 

 greater extent. Characteristic shapes are illustrated in Fig. 3. 



^^^^ ^^^^W ^0 /.V / V 



mm. 



(a) 



Fig. 3. Characteristic petal shapes in British Nuphar taxa. Circles mark the position of the nectaries. 

 (a) N. lutea; (b) N. intermedia; (c) " introgressed " N. pumila; and (d) N. pumila. Sources of material as 



in Fig. 2. 



