THE DICOTYLEDONES 1689 



and flies as well as short-tongued bees have all been observed to pollinate 

 this flower. 



The genus Tellima, with seven species occurring in Xorth-western 

 America, is noteworthy because the flowers are zygomorphic. This is 

 brought about by the great development of two petals to form wing-like 

 projections. The flowers are pollinated by butterflies and bees. The genus 

 Chrysosplenium with some sixty species is represented in Britain by C. 

 oppositifolium and C. alt erni folium. The flowers are tetramerous and 

 apetalous but are surrounded by yellowish bracts. The ovary is unilo- 

 cular with two parietal placentas and a deeply sunk receptacle. The 

 flowers are protogynous and are visited by small insects. 



The genus Parnassia occupies a rather anomalous position. It is 

 characterized by a conspicuous whorl of branched staminodes tipped with 

 false nectaries and by the ovary, which is unilocular with three or four 

 parietal placentas w^hich become axile at the base of the ovary. Some 

 authorities have therefore placed it in the Droseraceae, but others consider 

 it inadmissible in that family and prefer to regard it as a somewhat anoma- 

 lous member of the Saxifragaceae. 



The members of the next two sub-families, Francoideae and Hydran- 

 geoideae, are largely cultivated in gardens. Francoa and Teti/la come 

 from Chile, while the members of the Hydrangeoideae are found in North 



Fig. 1549. — Philodelphus coronarius. Flowers. 



America and eastern Asia. Philadelphiis coronarius, correctly known as 

 Mock Orange (Fig. 1549), is also referred to by gardeners as " Syringa", 

 a fact which causes confusion, for Syringa vulgaris is the botanical name of 



