FLORA OF SCOTTISH LAKES 
179 
Sparganium simplex, Hucls.^ V., VIL In similar situations to the 
last species, but usually much less abundant. Weak forms 
with elongated floating leaves also occur, usually in a foot or so 
of water. The var. longissimum, Fries ^ occurs at Loch Fitty. 
Sparganium natans, L., L, IV., V., VI., VII. Rather frequent in 
I. and IV. ; scarce elsewhere. Chiefly in peaty lochs of but 
moderate elevation. 
Sparganium minimum. Fries, I., IV., VI. Abundant in Area I., 
but in the other districts it is generally scarce and mostly con- 
fined to the hill lochs. A terrestrial form with leaves and 
inflorescences only a few inches high occurs at the margin of 
hill lochs in Area I. This small terrestrial form seems to be 
a reversion from the aquatic form towards a terrestrial type 
which was probably the habit of the ancestral stock. It seems 
to me that the most degenerate form of S. minimum and the 
most robust condition of S. ramosum are connected by numerous 
intermediates. Perhaps experimental culture, on the right 
lines, with S. ramosum would produce all the others. 
LEMNACE.^ 
Lemna trisulca, L., VII. Rare in the lochs, and only in those well 
sheltered by trees, with luxuriant marginal vegetation, and 
non-peaty water. 
Lemna minor, L., VII. Distributed as above, but more frequently 
met with in the lochs. It is a common plant in ditches, etc., 
in all Areas below about 500 feet elevation. 
POTAMOGETONACE^ 
Zannichellia palustris, Z., var. brachystemon. Gay, VII. Rare in the 
lochs, as a rule, but extremely abundant in Kilconquhar Loch. 
Potamogeton natans, L., I., II., III., IV., V., VI., VII. Abundant 
everywhere. The typical form occurs most plentifully in non- 
peaty lowland lochs. In peaty water it frequently becomes 
reduced, and then resembles forms of P. polygonifolius, 
although the two can usually be distinguished by characters 
exhibited by leaf, fruit, etc. 
Potamogeton polygonifolius, Pourr., I., IV., V., VI., VII. Abundant, 
particularly in peaty water. It varies greatly, and the typical 
form is usually less abundant than the form approaching P. 
natans. In the opposite direction of variation is a form which is 
very abundant in I^och Recar and the adjoining district (Area 
IV.). This is a very distinct variety, with elongated, rather 
pellucid leaves that are beautifully netted near the midrib, 
known^as var. pseudo-fluitans, Syme. 
