IRIDACEiE 



415 



resembling a petal, which arches over the corresponding 

 stamen and outer segment 

 of the perianth (Fig. 337). 

 In order to reach the honey, 

 which is secreted at the base 

 of the flower, insects have 

 to force their way between 

 this segment and the over- 

 arching style -arm. In so 

 doing the back will rub 

 against the outwardly 

 dehiscing anther. The re- 

 ceptive surface is the upper 

 face of a small ledge (st) on 

 the under side of the style- 

 arm. In backing out of 

 the flower a bee would only 

 come in contact with the 

 non -receptive lower face, 

 thus avoiding self-fertilisa- 

 tion ; on entering the flower fig. 337.—/™ Pseud-acoms. p, one of 



with pollen obtained on a the large outer petals ;«, anther of 



.J- ... •nil • * corresponding stamen ; s, the 



previous visit it will deposit corresponding style-arm arching over 



some of the pollen on the 



upper receptive face. We 



have two species — I. Pseud-acorus, with yellow, and 



/. fostidissima, with blue flowers. 



Gladiolus 



Flowers in a one-sided spike. Protandrous humble 

 bee flowers. Some of the flowers are female, the others 

 complete. The genus is represented in Britain by G. 

 illyricus, a Southern European species found in the New 

 Forest and the Isle of Wight. 



the stamen; st, ledge -like stigma. 

 Nat. size. 



SiSYEINCHIUM 



S. Bermudiana. — This is a North American 

 but is found in the South and West of Ireland. 



species. 



