20 Мовтем P. PorsiLp. 
They are almost without any exception lowland plants at the northern 
limit of their horizontal distribution. 
Our use of the expression lowland is relative, somewhat varying 
according to the locality. On the north side of big massives we denote 
as lowland a level as low as a couple of hundred meters above sea-level, 
on the south side and in protected places in the interior up to 400—500, 
occasionally even up to 600—700 meters above sea-level. The decisive 
proof to us has been whether the place had old concentrated vegetation 
or fresh moraine soil with open vegetation. 
Generally we have not stated the exact dates of flowering of 
the plants. After having kept, through a longer period of years, a journal 
of the earliest flowers from a single place and its vicinity we have arri- 
ved at the conclusion that a certain succession in the time of 
flowering can be proved for a majority of the arctic species, but that 
the actual dates may vary at least 6 weeks, namely just as much 
or more than the date varies at which the positive mean temperature 
begins. A few pronounced arctic species have no definite flowering 
season at all, they flower continuously throughout the period of vege- 
tation. 
As a general fact may be stated that the true arctic species (north- 
ern and widely distributed types) flower early, the subarctic or tem- 
perate late, provided that they attain to put forth flowers at all. When 
two systematically closely allied species belong each to its own type a 
characteristic difference, as to their flowering season, may be found, 
this fact being supported by numerous examples: 
Early flowering. Late flowering. 
Deschampsia caespitosa var. pumila D. alpina. 
Luzula confusa, L. nivalis. L. frigida, L. spicata. 
Stellaria longipes, St. humifusa. St. borealis. 
Potentilla Vahliana, P. nivea. Р. alpestris. 
Chamaenerium latifolium. Ch. angustifolium. 
Pirola grandiflora. P. minor, P. secunda. 
Pedicularis lanata, P. hirsuta. other species of P., the latest flow- 
ering is Р. euphrastoides. 
Erigeron eriocephalus. Е. unalaschkensis. 
Antennaria alpina. A. intermedia. 
etc. 
At another occasion we hope to come back to this subject, mean- 
while confining our attention here to statements of early and late 
flowering in such. cases where this seemed especially characteristic 
to us, just as we everywhere have stated absence of flowering as far 
as this was known to us. 
