10 Mindeskrift for J. Steenstrup. XXI. 



extend to Alaska and adjacent Islands. Of these Cl. asarifolia and CL Sibirica have 

 their widest area of distribution in the Rocky Mountain Region from British Columbia 

 to California, together with Cl. inegarrhiza, Cl. lanceolata, the remaining species of Limnia, 

 Alsinastrum, Naiocrene and Montiastrum except the Australian. On the Atlantic slope 

 Cl. Virginica and Cl. Caroliniana are distributed from Nova Scotia to North Carolina, 

 westward to Saskatchewan and Minnesota. The present distribution does point toward 

 the Rocky Mountains as being an important center of development of the genus Clay- 

 tonia; on the other hånd the occurrence of such alpine types as Cl. arctica and Cl. tu- 

 berosa in the mountains of Siberia, may indicate another, and much older center of di- 

 stribution. Glose to the arctic circle we find some of these large-rooted Euclaytonias, 

 and confined to the highest peaks: Cl. megarrhiza. In other words the very species that 

 illustrate the structure of arctic-alpine types are those of which the geographical range 

 is the widest: Altai, Alaska and Rocky Mountains. 



Considered from a morphological point of view these various species of Claytonia 

 exhibit several interesting types in which, however, the floral structure is very uniform 

 and almost constant, at least in the most essential points. The vegetative structures 

 are, on the other hånd, distinct, and indeed very pronounced in some sections. Some 

 correlation between structure and environment may be sought among those that exist 

 under extreme conditions, and the large-rooted species of Eiidaytonia do exhibit certain 

 characters in common with certain arctic and alpine types, viz. the deep root, the suc- 

 culent foliage, and low stature. The broad-leaved Cl. asarifolia and Cl. Sibirica illustrate 

 the sylvan type; the peculiar, very slender, bulbiferous Cl. parvifolia and Cl. flagellaris 

 resemble, in respect to habit, several other piants which inhabit moist rocks; in Cl. Cha- 

 missonis we have the structure of a number of bog-plants. But in respect to Cl. 

 Virginica and Cl. Caroliniana so very abundant in the woods, and blooming so very 

 early, the structure of these is rather unlike that of sylvan types in general viz. the deep- 

 seated root, and the succulent stems and foliage; they are, however, readily referable 

 to the genus, but they, certainly, are very distinct from the sylvan Cl. asarifolia and 

 Cl. Sibirica. 



We have, thus, in Claytonia a genus before us in which a number of structural pecu- 

 liarities are preserved wherever the species occur. As divided into sections the members 

 of the genus are classified in a very natural manner, and the distinctions are readily 

 perceived; the sequence, however, is not indicated. Owing to the wide gap in geogra- 

 phical distribution of certain species, it is very difficult to offer a demonstration of the 

 affinities from an evolutionary point of view. We wish we were in the position to de- 

 fine the groupsand the species in the same clear, instructive manner as Salomon Drejer 

 treated the genus Carex^) with formae hebetatae, centrales and desciscentes. In Claytonia 



^) Symbolae Caricologicae. Kjøbenhavn 1844. 



