ROBERT SMITH ON PLANT ASSOCIATIONS OF THE TAY BASIN. 203 
are assured, the plants have characteristics in harmony with those 
conditions. The leaves of many possess a thin cuticle and many 
stomata, so that transpiration goes on freely (Anemone, Oxalis, 
Circcea, Sanicula, Adoxa, Mercurialis, Paris, etc.). The grasses have 
their stomata on both surfaces of the leaf, and especially on the 
upper surface (Brachypodmin, Nhlium, Adelica, etc.^. No annual 
plants are regular inhabitants of the beech woods. All produce 
rhizomes, tubers, bulbs, or some such underground structures in 
which they may pass the unfavourable seasons of the year. Such 
subterranean growths are characteristic of places, like beech woods, 
where a loose, rich humus is present, and is continually being sifted 
and enriched by the burrowing of earthworms. 
Certain plants, although not necessarily shade-plants, can still 
thrive in these woods. Some, by means of climbing up the tree 
trunks, can raise their leaves to a region of greater light, whilst their 
roots still remain in the moist, porous soil, e.g., the honeysuckle and 
the ivy. Others lodge in forks or crevices of the trees, where a little 
humus may have gathered, and thus may come nearer the brighter 
light. Many such perched plants, or epiphytes, can be noted in a 
woodland walk, especially grass, fern (Polypodium indgare), dandelion, 
seedlings of trees, etc. Although in Scotland climbing plants and 
epiphytes form a small part of the wood-association, yet in the dark 
forest of the tropics they constitute—as lianas, epiphytic orchids, 
etc.—by far the greater part of the sub-dominant vegetation. Other 
wood plants obtain the necessary light by vegetating and flowering 
early in the season, before the leaves of the overhanging branches 
shut out the fuller light of summer; thus the ground under the bare 
leafless trees of April is brightened by the flowers of celandine, 
anemone, primrose, and wood-sorrel. 
Certain other habitats in our district present similar conditions 
of humus, moisture, and shade, e.g., shady dens and such places as 
the Woody Island. In these habitats, we find the same association 
of plants as in the beech woods. Almost all the plants mentioned in 
the following list as beech-wood plants are recorded in Mr. Barclay’s 
“ Flora of the Woody Island.” 
PLANT ASSOCIATION OF THE BEECH WOODS AND SHADY DENS. 
*Anemone nemorosa, L. 
Ranunculus Ficaria, L. 
*Viola silvestris, Reich. 
*Stellaria nemorum, L. 
*S. Holostea, L. 
^Geranium sylvaticum, L. 
*Oxalis Acetosella, L. 
Vicia sylvatica, L. 
*V. sepium, L. 
^Epilobium montanum, L. 
*These species have been found by Professor Flahault, of Montpellier, in beech 
woods on the Cevennes. 
