124 Knud Jessen. 



stris and Ruhus chamæmorus show characters in their leaf- 

 structure which undoubtedly should be regarded as agents 

 serving to prevent excessive transpiration, and yet they 

 grow in sphagnum-hog?, as do Ran. Pallasii and Ran. lapo- 

 nicus, the leaves of which I should characterize more 

 closely as mesomorphic-hydrophilous — a fact which 

 indicates that the adaptation of plants is not evidenced 

 solely by morphological conditions. 

 G. In the majority of the species the flowers are fairly con- 

 spicuous, least so in the Alchlmilla-fipecies and in Sibbal- 

 dia, but here they are gathered into more or less con- 

 siderable inflorescences; Sorhiis has richly flowering co- 

 rymbs, but in the remaining species the flowers are either 

 solitary or gathered into usually few-flowered cymes. 

 Two species have red flowers, viz. Pot. palustris, and Rub. 

 arcticus; the following have white flowers: Pot. tridentata, 

 Dryas, Rub. chamæmorus, Rub. saxatilis and Sorbus; the rest 

 have yellow petals. All the species undoubtedly produce 

 honey, which is secreted by the inner side of the hypan- 

 thium ; in several species a disk is developed {Pot. triden- 

 tata, Sibbaldia and Alchimilla). A slight perfume has 

 been noted in a few species only. Well-marked hercogamy 

 occurs in only a few of the species; Rubus chamæmorus 

 is dioecious, Dryas is andro-monoecious and Pot. palustris 

 is highly protandrous. The others, are homogamous or 

 have, at the most, a short preliminary unisexual stage. 

 Shght protandry has thus been observed in Pot. tridentata, 

 Pot. maculata, Dryas (some of the hermaphrodite flowers) 

 and Rubus arcticus, while Pot. anserina. Pot. emarginata{?), 

 Dryas (some of the hermaphrodite flowers) and Sorbus 

 are slightly proterogynous. It must be assumed that 

 self-pollination can take place in all species except in the 

 Alchimillas, Rub. chamæm,orus and Pot. palustris. There 

 are only very sparing notes to hand as regards direct 



