142 THE VEGETATIVE ORGANS 



' bulbils '. Axillary buds sometimes drop off and form new 

 plants ; good examples are found in cultivated species of 

 Lilium and sometimes in the Lady's Smock (Cardamine 

 pratensis). Reproduction by means of axillary tubers in 

 the Lesser Celandine has already been noticed (p. 64). 



A similar mode of vegetative propagation occurs in the 

 Wood Sorrel, and examples may often be seen in the Oxalis 

 so common in greenhouses. In some Ferns, numerous small 

 plantlets are produced on the fronds by vegetative budding. 



Social plants. Offsets and short axillary shoots form a 

 very effective means of spreading and give rise to densely 

 packed masses of plants which elbow out their weaker 

 rivals. Plants of the same species which grow in company 

 and cover a large patch of ground are termed social species. 



It is by such means that the beautiful flowery cushions 

 of rock-plants are formed on the mountains, and the 

 tussocks of sedges and grasses which produce the mono- 

 tonous Cotton-grass moors, and the grassy swards of the 

 hills and pastures, and thus give rise to some of the 

 most striking features in the vegetation of a country. 

 The extensive tracts of Bracken in the woods and on the 

 hill-slopes, the blue carpets of Wild Hyacinth, and lakes 

 and canals choked by water-weeds, are a few examples of 

 the spreading of plants over large areas, not by seeds, but. 

 by vegetative means. 



CHAPTER XI 



MOVEMENTS AND ATTITUDES OF PLANTS 



Movement is one of the common phenomena of life. We 

 usually look upon plants as stationary, and the power of 

 movement as characteristic of animals, but this is far from 

 a correct view of the case. Although a typical flowering 

 plant is fixed to the soil, all its growing parts, roots as well 



