CALYCIFLOR.E 231 



ation. The Mare's Tail, however, is frequently terre- 

 strial, as are some of the Starworts occasionally, and 

 so amphibious. 



There are nearly a hundred species placed in 

 eight genera, of cosmopolitan range. A large number 

 of the exotic types are natives of Australia. 



Their affinities are w^ith the Willow Herb group, 

 but they are also related to the Saxifrages. 



A marked characteristic of the group is the reduced 

 and small flowers. 



They are aquatic, herbaceous plants or shrubs. 

 The leaves are opposite, or alternate, or frequently, 

 in the British types, in whorls. There are no stipules, 

 as is normal in aquatic types. 



The flowers are very small, hermaphrodite or 

 unisexual. In the Milfoil the upper flowers may be 

 male, the lower ones female, and the intermediate 

 flowers hermaphrodite. They are regular, and the 

 stamens and perianth are epigynous, with the parts 

 usually in fours. There are bracteoles as a rule. The 

 perianth is in one or two whorls or absent. 



The calyx is superior, with two, four, or no sepals 

 or lobes, valvate or slightly overlapping in the bud ; 

 and it is adherent to the ovary. It may be practically 

 reduced to a mere ring without lobes. If petals are 

 present, as in Water Milfoil, they are very small, and 

 inserted on the calyx. They are wanting in Mare's 

 Tail and the Starworts. The stamens are four to 

 eight or only one (in the Starworts), and in the 

 complete flowers epigynous, obdiplostemonous, the 



