HERBERT JONES 



191 



Stamens (Fig. 2A 6) 



Filaments between 1 and 2 mm. and anthers small. 



Chromosome number 

 2n - 38. 



B. Callitriche obtusangula 



Leaf form (Fig. IB 1 and 2) 



Under conditions of still or slowly running water where the plant is usually en- 

 countered, obovate leaves about 1-5 cm. long by about 5 mm. broad are produced in 

 the floating crowns. 3 veins are present with possibly secondary branches. The surface 

 of the leaf bears raised ribs corresponding to the veins. More or less linear leaves are 

 produced on submerged axillary shoots. These leaves are 1 -veined, up to about 1 cm. 

 long and 1 to 2 mm. broad. Under conditions of submergence in running water (under 

 experimental conditions - Jones, 1955) linear leaves approxim^ating more to those of 

 Callitriche intermedia have been produced but without the pincer tip. 



Fruit form and styles (Fig. 2B 1-4) 



Fruits 1-6 mm. long by 1-5 mm. broad. In face view the fruits are narrowed slightly 

 towards the base. Grooves and keels are poorly developed, characters which readily 

 separate this species from the others described. Keels parallel. Styles terminal, about 

 4 mm. long and persistent. 



Bracteoles (Fig. 2B 5 and 6) 



Bracteoles of male and female flowers large and straight. 



Stamens (Fig. 2B 6) 



Filaments about 8 mm. and anthers large. 



Chromosome number 

 2n = 10. 



C. Callitriche stagnalis 

 Leaf form (Fig. IC) 



In its typical form the leaf enables the species to be readily identified, the typical 

 leaf being short (about 1 cm. long) and very broad (about 7 mm.). At least 5 veins are 

 usually present. Leaves of submerged axillary shoots are also obovate in form. The 

 first few leaves of the seedling are linear and 1 -veined (Jones, 1955). While no seedlings 

 have been grown by the writer beyond the 3 or 4 leaf stage, all seedlings of C. stagnalis 

 which have been seen under natural conditions have linear initial leaves which then grade 

 into very large multi- veined leaves, some 2-5 cm. long and 1 cm. broad (somewhat 

 of the form figured for C. obtusangula in Fig. IB 1). Subsequent leaves while still large 

 -some 2 cm. long by about 1-3 cm. broad - are of the 'typical' rounded form. The 

 large leaved form has always been found in the sterile condition and is probably a juvenile 

 form. The chromosome number of the large form is 2n = 10. 



Fruit form and styles (Fig. 2G 1-4) 



Fruits 1-6 mm. long by 1-7 mm. broad. In face view the fruits are narrowed slightly 

 towards the base. Grooves and keels are well developed, the keels diverging noticeably 



