8 Some Aspects of PI ant- Life. [Sess. 



II.— SOME ASPECTS OF PLANT-LIFE. 



By Mr VVM. C. DOUGLAS, M.A., B.Sc. 



(Communicated, Dec. 18, 1912.) 



It does not need a very extensive study of plants to show 

 us that among plants as among animals there are well- 

 marked communities or associations. 



I would invite you to look at some of the most typical of 

 these plant communities, to notice the chief features they 

 present, and to consider the explanation most commonly 

 accepted of the chief cause that is at work modifying firstly 

 the form of the plant (deciding whether it shall be herb or 

 bush or tree), and secondly, the formation to which the plant 

 belongs (i.e., the general aspect of the plant community, — 

 desert community, grassland, or woodland). 



From the primeval sea all existing forms of life are believed 

 to have been originally derived. Leaving the sea and 

 examining the rocky shore region, one can hardly help 

 noticing a sort of zonal arrangement of plant-life. On the 

 rocks rarely uncovered by the tide are anchored the long 

 laminarias or tangles, bladder- wrack, and Fucus serratus : on 

 the rocks alternately covered and uncovered flourishes the 

 dark-purplish Chondrus crispus ; and above this zone, and 

 oftener uncovered than covered, are green filamentous and 

 unicellular algse. 



A view of the east side of G-ranton breakwater seems to 

 support this statement. I have noticed that bathers find on 

 the middle zone of short crisp weed a secure and tolerably 

 dry footing, while the bladder- wrack and other weeds lower 

 down are slippery and insecure. 



The sea-shore gives us a good idea of a typical desert 

 region. It is true that we do not have in our latitudes the 

 hot and dazzling sunshine of the tropics, but the appearance 

 of our sea-shore plants is quite desert-like ; the vegetation of 

 the sparsest kind, coarse couch-grass, fleshy-leaved plants like 

 stonecrops and sea-kale, glassworts, and prickly-leaved sea- 

 hollies, all showing adaptation to dry arid conditions in their 

 reduced leaf-surfaces, or thick fleshy leaves and stems. Here 



