350 ECOLOGY 



the seasons forms an interesting study. In the winter, tree 

 and shrub layers stand out in sharp contrast, as in the case 

 of leafless Oak and evergreen Holly. Still more striking 

 is the spring aspect of Ash and Hazel, the early bright- 

 green foliage of the latter being very conspicuous against the 

 grey branches and black unopened buds of the Ash. The 

 green winter carpet of grasses and mosses is followed in 

 the spring by low-growing plants (Fig. 225) like the Blue- 

 bell, Anemone, Primrose, Cowslip, and Celandine, to be 

 succeeded in the summer by the taller-growing Bracken 

 and other ferns. Meanwhile, the leaves of the trees are 

 expanding, and by their ever-deepening shade, protect 

 the tender plants of the ground flora. 



Complementary societies. The diagram (Fig. 227) will 

 help us to appreciate the significance of such adaptations 

 in the ground flora of an Oak wood where the three plants 

 illustrated commonly grow in close association. In the loose 

 leaf-mould on the surface run the rhizomes of the Soft-grass. 

 Beneath this, in the dark soil containing much humus, are 

 the rhizomes of the Bracken, while in the fine yellow loam 

 below are the bulbs of the Bluebell, though young bulbs 

 on their way downwards may be found in the other two 

 layers. In November the young green blades of the Soft- 

 grass appear, and through the winter and early spring form 

 a bright green carpet. Meanwhile, the leaves of the Bluebell 

 come above ground, to be followed in the early spring by 

 a wealth of flowers (Fig. 225). Towards the end of the 

 flowering period, and as the fruits are ripening, the Bracken 

 unfolds its fronds, and raised on tall stalks above the tops 

 of the young Bracken are the flowers of the Soft-grass. 

 In the late summer and autumn the mature Bracken-fronds 

 form a continuous cover. Eventually they die down to 

 form a warm winter carpet. Thus their soil-requirements, 

 their modes of life, their periods of active vegetative 

 growth, their times of flowering and fruiting, are for the 



