THE REPRODUCTIVE ORGANS 



MOEPHOLOGY OP THE FlOWEE 



As a preliminary to the account of the development of the flower 

 and of the reproductive organs, it will perhaps be in the interests 

 of clearness to preface a short description of the mature flower. 

 In this connection I shall also take occasion to discuss briefly some 

 of the more important morphological aspects of the flower. 



The flowers of Ruppia maritima are small, (3—5 mm. in diameter), 

 consisting of two stamens and generally four pistils, with no perianth, 

 and are borne in a pair at the apex of the peduncle, occurring 

 one above the. other, on opposite sides of the rhachis (PL IX, fig. 49). 

 The iiaflorescence is thus spadix-like, a type which is more pro- 

 nounced in Potamogeton and Zostera. 



The mature stamen resembles two thick, rounded, semicircular 

 bands closely appressed to the rhachis (PL IX, fig. 49), and meeting 

 each other on opposite sides of it, each band being the half of an 

 anther. In the Bonn Textbook (1908, p. 422), these anther-halves 

 are called " thecae," and because this term is shorter and more specific, 

 it will be used in this paper. A comparison with figure 474 of 

 that textbook (1908, p. 422) demonstrates how a stamen of this 

 sort could easily be evolved by a gradual separation of the thecae. 

 In Ruppia their complete separation at maturity has led them to 

 be interpreted as single stamens with bilocular anthers, for 

 Roze (1894, p. 476) says: "Je n'ai pu y parvenir, car je n'ai 

 jamais trouve, dans les antheres meme jeunes, une adherence, 

 une soudure quelconque qui le (i. e., cette diminution du nombre 

 des etamines) fit supposer. Et il est bien certain qu'a la maturite 

 des organes, il est impossible de ne pas reconnaitre que chaque 

 fleur presente quatre etamines parfaitement libres, ce qui est le point 

 essentiel." PL IX, fig. 50, however, gives a correct idea of the 

 morphology of these thecae ; for at this young stage the connective 

 shows clearly that the structures on each side of it are merely the 

 two thecae of the same stamen. 



At this point, it is interesting to note in PL IX, fig. 50 the extension 

 of the connective out beyond the plane of its attachment to the 

 thecae, forming what is described by Irmisch (1851, p. 84) as " ein 



