Table 2
Table 2. Silicon and aluminium content of the cell walls of five tissues of mature needles of six conifer taxa as determined by EDX microanalysis and expressed as mean values in mmol/kg (n= 5)

Conifer species
Soil pH
Leaf age (yr.)
Element
Epid-
ermis (a)
Hypo-dermis (b)
Meso-
phyll (b)
Endoder-mis (a)
Transfusion tracheid (b)
Pinus strobus L., White pine
4.2
2
Si
200
200
1500
500
5800
[35,36]
Al
15
5
25
15
45
Tsuga canadensis (L.) Carr.,
4.2
3
Si
60
1200
330
300
1000
Eastern hemlock *
Al
60
65
10
20
40
Picea glauca (Moench.) Voss,
4.2
5
Si
280
630m
nd
1100m
nd
White spruce [37]
Al
70
35m
nd
25m
nd
Abies balsamea (L.) Mill.,
4.2
4
Si
75
25
15
25
nd
Balsam fir [38]
Al
70
15
30
10
nd
Larix laricina (Du Roi)
6.7
1
Si
1900
250
60
25
25
K. Koch, American larch [39]
Al
60
20
10
15
18
Larix decidua (L.) Mill.,
6.7
1
Si
2300
700
25
25
15
European larch [39]
Al
30
15
12
15
10

Unless otherwise stated all determinations were conducted using frozen hydrated sections from the needle tip.
(a), outer tangential wall; (b), radial wall; m, mid-point of needle; nd, not determined.
*, approx. values derived from unpublished data; all other data derived from our previous publications [35,36,37,38,39] .