THE GENOTYPICAL RESPONSE OF THE PLANT 295 
of the upper epidermis, are considerably distended (fig. 76c). The 
Stenshuvud cliff form has leaves of about the same thickness and 
structure but the cells are less distended than in the west coast 
cliff forms. 
There are also marked differences in the time of flowering and 
fruiting in the different forms. The dune forms begin to fruit as 
soon as the first part of September, while the cliff forms do not reach 
this stage until the last part of September or the first part of October. 
The inland form is intermediate in this respect. 
The above discussed cultivations of Hieracium umbellatum, col- 
lected in different habitats, tend to bring out the facts that the heredi- 
tary variation within the species is considerably marked and that the 
variations occurring within the limited geographical area dealt with 
roughly group themselves in five types, viz.: 
a. The dune type of the shifting dunes from the drift-sand and 
white dunes along the western coast and the Sandhammar region. This 
type comprises individuals with rather narrow leaves and slender, less 
erect, sometimes more or less prostrate, stems. The power of shoot- 
regeneration during autumn is marked. The rather tough and thick leaf 
shows 3—4 layers of palisades. The fruiting stage is reached in the 
first part of September. — The form growing on the lacustral dunes at 
Oved is probably to be referred to this type. 
b. The dune type of the arenacious fields and stationary dunes 
from the eastern coast strip of Scania. The individuals of this type 
closely resemble the dune form of the shifting dunes but differ in the 
extreme prostrateness of their stems. The power of shoot-regeneration 
during autumn is less marked or is entirely wanting. 
c. The sea-cliff type of the west coast. This type comprises 
broad-leaved individuals, more or less prostrate. The cells of the leaves 
are considerably distended. The growth-form of the plants is contrac- 
ted and bushy. The fruiting stage is first reached in the latter part 
of September or in the beginning of October. 
d. The sea-cliff type of the east coast (Stenshuvud) resembles the 
preceding form as to the broadness and thickness of the leaves. The 
growth-form, however, is quite different; the plants are tall and almost 
as erect as plants of the inland type. The fruiting stage is reached at 
the same time as in type c. 
e. The woodland type of the interior from open, herbiforous 
