14 PELOPHILOUS FORMATION OF LEFT BANK OF SEVERN ESTUARY. 
Within these leaves the content of salt is very high. They 
possess glabrous cuticles, not appreciably thickened nor with the 
stomata sunk below the surface, neither is the number of stomata 
present below the general average for an herbaceous plant, so 
that in these respects their characters are not xerophytic. In the 
case of Aster Tripoliiun, counts of the stomata were made for 
several leaves, and in this dorsi-ventral leaf the number of stomata 
is somewhat greater on the upper surface, again by no means a 
xerophytic character. 
TABLE I. 
Stomata per square centimetre. 
Leaf No. 
Upper Surface. 
Lower Surface. 
i 
444° 
3810 
2 
533o 
2270 
3 
4820 
3°3° 
4 
7060 
6070 
5 
6150 
5080 
6 
4920 
3 6 3° 
7 
6570 
3120 
8 
457o 
2080 
9 
6940 
3400 
IO 
6050 
4260 
1 1 
5200 
375° 
12 
4600 
356o 
Average number per 
square centimetre 
••• 555° 
3670 
The glabrous character of all the plants of this formation is a 
striking feature ; in the zones that usually undergo submergence 
I have not found one specimen of a plant bearing hairs, though 
on the same formation at Clevedon, lower down the coast, I have 
found a single specimen of the shrub, Obione portulacoides Moquin, 
growing. This absence of hairs I am inclined to associate with the 
muddy saline water in which the plants are periodically immersed, 
though without experiment it is impossible to speak definitely. 
Owing to the scouring action of the tidal currents the channel water 
always carries a large amount of suspended matter with it ('557 
grs. per litre is stated by Hann. quoted by Moss 1 ), and if plants with 
hairy surfaces are left suspended in this liquid for some time, 
the mud rapidly deposits in a thick film upon them, and sub- 
sequently cakes and sticks very firmly, perhaps partly on account 
of the salt in the water. 
Many of the plants growing in the formation are often seen to 
be very muddy, but after comparing their appearance with that 
of hairy plants suspended in the same liquid and then left to dry, 
1 Moss loc. cit. p. 18. 
