Geoscience Reference
In-Depth Information
aligned
xylem
aligned
xylem
pith
primary
cortex
(
h
)
vascular
strands
cortex
(
c
)
pith
branches
(
g
)
D
MP
D
MS
(
f
)
genesis
(
a
)
strands
cortex
D
MP
genesis
roots
fused
E
pith
genesis
A
roots
free
(
e
)
primary
cortex
Ground
surface
D
MP
fused
roots
E
(
b
)
(
d
)
Fig. 4. Growth model for self-supporting cladoxylopsid stems. (a) Right: main primary growth phases (E, M, A)
and their relative length. Two double arrows indicate the possibility for late tangential increase in the basal
obconical part of the stem. Left: organs borne by the stem. After emission, roots run through stem tissues and emerge at
base where they remain fused before separating distally. Roots increase in diameter proximally then become cylindical.
