Hart — On the Mountain Flora of Ireland. 
561 
species which range in Great Britain throughout the three agrarian 
zones, and yet do not occur in my list of Irish mountain plants. Those 
which fulfil these conditions will be found to be chiefly species which 
under no circumstances ascend mountains. In many cases they are 
maritime. Such plants should all, however, occur in the north and 
north-east of Ireland, which corresponds in the lowland parts to 
Watson's super- agrarian zone, while the lowland parts of southern 
and south-western Ireland will fall under the mid-agrarian. The 
difference in these two zones is about three degrees of latitude, or 
a thousand feet of elevation. 
Certain exceptional southern and western species which oceur in 
the extreme south-western and western parts of Ireland tend to prove 
that the climate there verges upon that of Watson's infer-agrarian 
zone in Great Britain ; but the species are few and hardly sufficiently 
prevalent to stamp their character upon the whole flora of the limited 
areas in which they occur. 
Let us see now how far the above deductions are borne out by the 
facts of the case. I have already stated that out of about two hundred 
species characteristic of Watson's lowest zone (infra-agrarian) in 
Britain, and not extending above it, hardly a tenth occur in Ireland a& 
native plants. Those which do are : — 
Matthiola sinuata : south-east. 
Helianthemum guttatum (var. Breweri) : south-west. 
Viola curtisii : coasts of all Ireland ; maritime ; distribution mis- 
understood in Watson's time. (?) 
Elati^ie hydropiper : north-east ; hardly representative of the 
group. It occurs on the Continent in iN'orway and Sweden, 
and like other aquatics is considerably independent of 
climate. 
Geranium rotundifolium : south-west. 
Trifolium subterraneum : south-east. 
T. glomeratmn : south-east. 
MijriopliyTlum verticillatmi : throughout Ireland, but aquatic, and 
therefore not so dependent on climate. 
Ruhia peregrina : southern half of Ireland. 
Biotis maritima : south of Ireland. 
Erica ciliaris : west. 
Cicendia fiUformis : south-west. 
Sihthorpia europoea : south-west. 
