HERBERT JONES 



187 



the fruit is viewed from above, 4 lobes are seen, corresponding to the 4 cells. The 

 prominence or otherwise of these lobes and whether they diverge from the point of 

 insertion of the styles or are parallel are of considerable diagnostic importance. Unfor- 

 tunately, a distinction is made between a less prominent lobe (termed a keel) and a more 

 prominent lobe (or wing), the dividing line between the two states being somewhat 

 obscure. In the present description, the margins of the lobes are described as keels. 

 These are barely discernible in C. ohtusangula (Fig. 2B 1-4). In C. hermaphroditica (Fig. 2D 

 1-4) a wing is present in addition. In the young fruit the keels may not be easily seen but 

 in the mature fruit, due to the maturation of the seed within the more or less transparent 

 fruit wall, the keels become more prominent. In any case, the young fruits of all 4 species 

 to be described are remarkably similar and should not be used for identification. Where 

 grooves are referred to these relate to the indentations between lobes - in fact between 

 the original 2 carpels, whose positions are indicated by the style origins (Fig. 2C 3). 



In this description a distinction will be made between terminal styles (Fig. 2C 1) 

 and lateral styles (Fig. 2A 1). Again, some species have persistent styles and ethers 

 have styles which fail early. It appears to the writer that the terminal style is associated 

 with persistence and the lateral style with early falling. All styles are initially terminal. 

 In C. intermedia for example, the lobes grow over the styles so that these appear lateral. 

 Constriction may result in early fall. In C. stagnalis, the lobes grow under the styles 

 keeping them in an erect, terminal position. Here there is no constriction and the styles 

 persist. 



Methods and materials 



Material of C. intermedia (obovate-leaved), C. obtusangula, and C. stagnalis was 

 obtained from a drainage ditch at Tanybwlch near Aberystwyth, Cardiganshire. Linear- 

 leaved material of C. intermedia was obtained from the river Rheidol near Aberystwyth. 

 The floral characters of the linear-leaved form agreed with that of the obovate-leaved form. 

 These forms were also shown to be identical by means of transplant experiments (these 

 are described elsewhere - Jones, 1955). C. hermaphroditica was gathered from the outflow 

 of Llyn Maelog in Anglesey, probably its southernmost locality in Britain. 



In order to arrive at a ' typical ' fruit form, ten fruits from each species were drawn 

 silhouetted in face view with the aid of a camera lucida. The fruits were mature and in 

 the case of each species were from several shoots. The average length and breadth of 

 the ten fruits were calculated and a ' typical ' fruit constructed diagrammatically to these 

 dimensions, taking into consideration the general form shown by the ten fruits. Side 

 views and views from above were constructed with a binocular microscope, a camera 

 lucida being used initially to find the correct proportions. The views from above may 

 not, in all cases, show the full thickness of the fruit as this had to be cut transversely 

 and the top part placed on a slide. Otherwise it was found difficult to maintain the 

 fruit absolutely upright. 



Lengths of styles (mean of 10 styles from 5 fruits) were recorded where the fruit 

 was mature and where the style was evidently entire. At later stages of fruit development, 

 the distal portions of styles were commonly broken off. Filament lengths were taken 

 from stamens with mature anthers. The length quoted is an average of 10 filament 

 lengths, except in C. hermaphroditica where stamens were scarce. Here only 2 stamens were 

 found with dehisced anthers and where it could be assumed that the filaments were of 

 maximum length. Bracteoles were found to be very variable in size and the bracteoles, 

 illustrated in Fig. 2, 5 and 6, represent the largest recorded. Chromosome numbers 

 were estimated from root-tip squashes. 



Leaves were fixed in formalin-acetic-alcohol, and were sufficiently transparent after 



