CCV.— HEATHS. 
Erica cinerea Linne and E. Tetralix Linne. 
T here are some striking contrasts between the closely related genera Calluna 
and Erica. The former genus is practically monotypic, none of the variations 
of Calluna vulgaris in such characters as pubescence being apparently sufficient to rank 
as species. Erica , on the other hand, numbers upwards of four hundred species. 
Calluna again is essentially and exclusively northern, being confined to Europe, 
exclusive of Turkey and Greece, the north-west of Asia, the Azores, Greenland, and 
small areas from Newfoundland to Massachusetts, being the only representative of 
the Sub-Family Ericoidea in North America, and is thus appropriately known as Ling , 
a name derived from the Scandinavian languages. Erica , on the other hand, besides 
twelve species in Europe, some of which extend into northern Asia, North Africa, 
Abyssinia, and British East Africa, has numerous representatives in the rich and 
mainly xerophytic flora of South Africa. Of the six species wild in the British 
Isles, four are confined to the extreme south-west, the large-flowered and beautiful 
E. ciliaris Linn£ occurring in Dorset and Cornwall, the Cornish Heath (£. vagans 
Linn6) in the west of Cornwall, the Mediterranean Heath (£. mediterranea Linnd) 
in Mayo and Galway, and Mackay’s Heath (£. Mackayi Hooker) in Connemara 
(Galway) only. On the continent of Europe these four species occur only in the 
west, in western France, Spain, and Portugal ; while the two species represented on 
our Plate, which are widely dispersed over the whole of the British Isles, are also 
essentially western, E. cinerea extending only to northern Italy and Germany and 
E. Tetralix as far east as Poland. Sir Joseph Hooker accordingly suggested 
“ the probability of the South African flora being represented all along the highlands of eastern Africa, from Natal to Abyssinia ; 
and further, seeing that most of the South African plants found in the Cameroons are also natives of Abyssinia, it would 
appear probable that the migration of these to the Cameroons was by and through Abyssinia.” 
Obviously the so-called Atlantic or Lusitanian florula or subordinate geographical 
group in our own flora, of which Arbutus and the above-mentioned Heaths are most 
prominent representatives, may well have extended northward along the same route. 
Our European Heaths do not extend into the Arctic regions, though Ling does grow 
in Iceland. 
The genus Erica is said to take its name, Dioscorides’s Greek 'EptUr), Ereike , 
from iptLKOj, ereiko , I break, apparently because, growing as it does amidst finely 
broken sand, it was supposed, like the Saxifrages, to be useful in cases of calculus. 
Beyond the making of brooms and thatch, and some slight use in peasant industries 
for dyeing, the group is not now put to much use by man, but is valued chiefly for 
its beauty. The woody rhizome of E. scoparia Linn£, the Eruyere of the French, is, 
however, the material of “ briar ” pipes. 
We are yet far from a complete knowledge of the relations between soil- 
bacteria and Flowering Plants ; but the species of Erica share in general the dislike 
