THE 
HEW PflYTOIiOGIST. 
Vor.. XV, Nos. 3 & 4. March & April, 1916 . 
[Published May 18th 1916]. 
THE VEGETATIVE ANATOMY OF MOLINIA CAERULEA, 
THE PURPLE HEATH GRASS. 
By Rev. T. A. Jefferies, F.L.S. 
[With Nine Figures in the Text]. 
HE following account of the structure of Molinia ccerulea 
1 results from a study of the grass carried out at the suggestion 
and under the guidance of Dr. T. W. Woodhead of the Huddersfield 
Technical College. The inquiry has proved most fruitful, especially 
from the ecological point of view, and an outline of the main results 
in that direction has already been published (2). The anatomy of 
the species, however, is only slightly less interesting than the 
ecology and shows important relations to it. Hence it has been 
deemed advisable to make the following details available as soon as 
possible. 
The Purple Heath Grass (Fig. 1) is a perennial, growing in wet 
but well-drained situations in the fens and on the moors. It 
dominates miles of the Pennine uplands on siliceous soils, frequently 
to the exclusion over large areas of all other flowering plants. 
Where the drainage becomes blocked it yields place to such species 
as Eriopliorum vaginatum and Empetrum nigrum; where the 
water supply weakens the ground is held by Nardus stricta, Calluna 
vulgaris, etc. Typically Molinia forms circular tussocks from 8 to 
20 cm. in diameter at the base, and raised to a similar height above 
the soil; tussocks may be found, however, as much as 75 cm. 
across. The rhizomes are closely interlaced at, or a little above, 
the level of the soil, and below these we have the tangled mass of 
adventitious roots. The flat, narrow leaves generally stand up 
boldly and almost perpendicularly from 20 to 40 cm. above the 
rhizomes. Above the leaves, throughout the latter half of the year 
and often persisting through the next season, rise the inflorescences, 
their close-packed panicles looking like spikes, and upheld on tall 
