5 mm
belowground
structures
a
b
c
d
h
e
2 cm
Silurian
Devonian
0
0
4
-
0
2
4
-
Million Years
0
6
3
-
0
4
3
-
40 cm
50 cm
soil surface
10 cm
f
g
2 cm
Fig. 21.3 Conceptualized
changes in above- (crosshatched) and below-organ
modifications during the
Silurian transition to the
Devonian Period. (a)
Zosterophyllum (b) Rhynia
(c) Drepanophycus (d)
Aneuophytes (fern-like
plants) (e) Other fern-like
plants, some tree-like and
deep-rooted (f, g) (h)
Archaeopteris and related
plants with deeply
penetrating roots. Modified
from Xue et al. (2016)
432
S. Kouas et al.