THE SPECJES AND THE VARIETY AS ECOLOGICAL UNITS 109 
dy. 
bitats and now in culture tends to bring out the 
fact that at least three groups of types of this 
plant are differentiated in southern and middle 
Sweden. The ordinary variety (fig. 4) grows in 
open, herbiforous woods, the second grows on 
the dunes along the coast (fig. 5); a third va- 
riety occurs in arenacious fields in certain parts 
of the south (fig. 6). 
When sets of turfs of 
these groups are cultivated side by side, their 
Fig. 5. Hieracium umbellatum, dune variety 
(about !/s nat. size). 
respective and distinctive characters are at once 
seen. The material from the woods represents 
erect, rather broad-leaved forms, while the 
plants from the dunes show more narrow- 
leaved, less erect, and strongly shoot-re- 
generating forms. The third variety, 
which is perhaps to be called H. 
umbellatum var. dunense, REYN, 
is a prostrate plant with much 
hairiness at the base of the 
stems and is unable to re- 
generate during autumn. 
There is great va- 
riation within the 
groups in regard to 
the shape of the leaf 
margin, the inflore- 
scence etc., but the 
groups as such are 
quite distinct in the 
majority of cases. 
The close rela- 
tion of these groups, 
or varieties, to the 
habitat presents a 
most interesting stu- 
The varieties are sometimes found growing within a short distance 
from each other, as for instance in the south-east corner of Skâne (south- 
ernmost Sweden), where woods, dunes, and sandfields alternate. The 
prostrate variety is found growing abundantly on the sandfields north 
of Kivik. This variety is succeeded by the variety typical cf the woods 
