ROBERT SMITH ON PLANT ASSOCIATIONS OF THE TAY BASIN. 
Scabiosa succisa, L. 
Antennaria dioica, R. Br. 
Achilles Ptarmica, L. 
Campanula rotundifiora, L. 
Vaccinium Vitis-Id^a, L. 
V. Myrtillus, L. 
Erica Tetralix, L. 
E. cinerea, L. 
Trientalis europsea, L. 
Veronica officinalis, L. 
Euphrasia officinalis, L. 
Thymus Serpyllum, L. 
Rumex Acetosella, L. 
Empetrum nigrum, L. 
Juncus squarrosus, L. 
J. conglomeratus, L. 
Luzula campestris, D,C. 
Scirpus caespitosus, L. 
Eriophorum vaginatum, L. 
E. angustifolium, Roth. 
Carex (numerous species). 
Anthoxanthurn odoratum, L. 
Agrostis vulgaris, With. 
Deschampsia flexuosa, Trin. 
Molinia varia, Schrank. 
Festuca ovina, L. 
Nardus stricta, L. 
Juniperus communis, L. 
Lomaria Spicant, Desv. 
Lycopodium Selago, L. 
L. clavatum, L. 
L. alpinum, L. 
In these plants we see many adaptations to the hard and varied 
conditions of life on the moors. The wind sweeps cold and strong 
over these great areas, drying up all weakly plants. In summer, the 
sun may beat down intensely until the ground is dry as tinder; 
and again, for days, the moors may be enshrouded in a cold, still 
mist, when little transpiration is possible. The chief moor-plants 
possess small leaves with much reduced surface (Calluna^ Erica^ 
Juniperus^ Einpetrutn^ etc.^, often evergreen, and enclosed in thick 
glazed cuticles. A number of the grasses can in-roll their leaves 
during drought, and thus reduce their surface (Nardus^ Festuca^ 
Agrostis)^ and the heaths have their leaves permanently back-rolled.* 
SUCCESSIONS OF ASSOCIATIONS. 
In a well-defined association there occur, as has already been 
pointed out:— 
1. A chief or dominant species; 
2. One or more sub-dominant social species, restrained from 
occupying the whole space by conditions of soil and 
climate, or by the greater power of the dominant species; 
3. Intermingled solitary species {i. e., never living socially); 
4. Symbions—in the wide sense, including saprophytes, para¬ 
sites, shade-plants, epiphytes, etc. 
Between the dominant and sub-dominant species a great struggle 
* A simple account of these adaptations can be found in Professor Miall’s 
“Round the Year,” or in Kerner and Oliver’s “Natural History of Plants;” 
perhaps the most important work on the subject is that by Niedenzu (Engler’s 
Botanische Jahrbucher, xi. 1889-90, pp. 134-263). 
