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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. megarrhiza, 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
Claytonia; on the other hand the occurrence of such alpine types as Cl. arctica and Cl.
tuberosa in the mountains of Siberia, may indicate another, and much older center of
distribution. Close 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 hand, 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 Euclaytonia do exhibit certain
characters in common with certain arctic and alpine types, viz. the deep root, the
succulent 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 plants which inhabit moist rocks; in Cl.
Chamissonis 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
deepseated 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
peculiarities 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
geographical 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
define the groups and the species in the same clear, instructive manner as Salomon Drejer
treated the genus Carex[1] with formae hebetatae, centrales and desciscentes. In Claytonia
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