262 
Groom.—Remarks on the Oecology of Coni'ferae. 
either in decreasing the resistance to flow or in providing wider reservoirs 
that more readily part with the contained water. 
Hence, it remains to inquire if the evergreen habit associated with 
narrow water-conducting tubes provides an efficient and successful 
mechanism. 
In the genus Quercus the evergreen species show a wide range of 
habitat and general distribution. Evergreen oaks occur in dry habitats 
(Mediterranean and North America), ascend to 11,000 feet in the 
Himalayas, descend to the humid forests on the lower slopes of the 
Himalayas, and occupy truly tropical situations in the forests of Indo- 
Malaya. They therefore show a wide range of habitat and general 
distribution. 
Evergreen northern Coniferae, which have more reduced individual 
leaves, vie with or even surpass dicotylous trees in range of habitat and 
distribution. It is well known to foresters that sundry Conifers, including 
the Scots pine, can thrive on soils too poor for the successful cultivation of 
dicotylous forest trees. In the Northern Hemisphere, not only in temperate 
but in tropical regions, they take possession of less favoured sites on moun¬ 
tains and hills. But on more favourable situations on mountains in Europe, 
North America, and Asia they can give rise to forests and defeat dico¬ 
tyledons. In some instances at least, the Conifer defeats the dicotyledon 
in favourable sites ; thus in the battle between two shade-enduring species, 
Abies pectinata and the beech, the former is sometimes the victor and 
drives its foe before it (for instance, in the Schwarzwald in Wurtemberg). 
R. Gradmann (’00) has given an interesting analysis of the struggle 
between Picea excelsa and Fagus sylvatica in southern Germany. He 
shows that the victor below 400 metres is the beech, but above 1,000 metres 
the spruce; while the belt between 400 and 1,000 metres altitude is the 
region of a ceaseless struggle in which soil often decides the result, as 
the spruce is usually victorious on sandy soil and the beech on calcareous 
soil, but even on the latter soil heavy battalions of spruce may drive 
the beech on to the driest sites. Other examples of the defeat of dicotyle¬ 
dons (oak for instance) by spruce might be given. In India, Pinus longi- 
folia , P. Khasya , and P. Merkusii form forests at altitudes at which tropical 
vegetation is wont to prevail. 
Again, judged by range of the single species, the coniferous mechanism 
shows its efficiency. Juniper us communis in its ordinary form extends 
from arctic regions and alpine altitudes in the cold-temperate region down 
to the Mediterranean shores, where it reaches sea-level. As an oligotrophic 
plant it grows on sunny rocks, the driest dune-sands, dry heaths, and 
soaking sphagnum bogs ; yet it can thrive on good soil and in less lighted 
places, and grow as underwood even in shady forests of silver firs and beech 
in northern Europe, or in moist misty country in southern Europe. 
