Rev. T. A. Jefferies. 71 
tendency to store up food reserves in various members—cord roots, 
rhizomes and basal internodes, to which might be added the seeds, 
and ( d ) the powers of adaptation which seem to lie latent in every 
part of the organism, e.g., chlorophyll in roots, rhizome elongation, 
and galled bases. 
3. Finally the biological value of these structures may be 
stressed as relating them to the facts of distribution, etc. set out in 
the study of the plant's ecology (2). (a) The huge root system, the 
distribution of root hairs, the presence of mycorhiza, the abundant 
xylem, and the thin leaf plentifully supplied with stomata on both 
sides, indicate great powers of transpiration and a strong hold on 
the resources of the soil, (b) These in turn, when correlated with 
the wet habitat, flat leaf, and for a moorland plant, exceedingly 
large amount of assimilating tissue, suggest the ability to make 
food quickly and take full advantage of the short summers on 
the hills, (c) When to this we add the highly developed motor 
mechanism, the efficient and abundant storage tissue, and the 
evergreen character of the stems, we see how the disadvantage of 
delicate leaves is compensated, (d) Lastly the mechanical strength 
of the whole plant, together with its compact circular tussocks, 
gives it a power of resistance to wind and flood which go far to 
explain the success of Molinia ccerulea as a coloniser and often a 
dominant species on our exposed uplands. 
4. On the other hand, when studied in relation to its habitat 
on the Pennines, certain weaknesses appear. (a) The delicate 
nature of its ribbon leaf results in widespread withering of the leaf 
tips in the drying winds, (b) Its early development, by means of 
food reserves, exposes the young foliage to excessive cold. ( c) 
Probably in consequence of the preceding, in cold seasons etiolation 
is so abundaut that wide stretches look yellow rather than green 
and in most years throughout the season “ autumn ” tints appear 
on all the leaves. 
LITERATURE REFERRED TO 
1. Grimshaw, Percy H. “ Oligotvophus Ventricolus Rubs., a new Yorkshire 
Gall-Midge.” The Naturalist, 1914, pp. 333-6. 
2. Jefferies, T. A. “ Ecology of the Purple Heath Grass (Molinia ccBYXilea)." 
Journal of Ecology, Vol. 3, 1915, pp. 93-109. 
3. Lewton-Brain, L. “ On the Anatomy of the Leaves of British Grasses.” 
Trans. Linn. Soc. Bot., Vol. 6, 1904. 
4. Ward, H. Marshall. “ Grasses,” 1901. 
5. Woodhead, T. W. “ Notes on the Bluebell.” The Naturalist, 1904, 
pp. 41-8 and 81-8. 
( t> “ Ecology of Woodland Plants in the Neighbourhood 
of Huddersfield.” Journ. Linn. Soc. Bot., Vol. 37, 
333-406. 
