26 THE BOOK OF NATURE STUDY 



may be recognised by their backward curve, and by being com- 

 posed of two tubes, clearly seen when the leaf is cut across. 

 The tall flower-stem arises from the centre of the rosette, and 

 lengthens until the lowest flower is well above the water. The 

 flowers are pale blue ; the corolla is inclined to be two-tipped, 

 and the five anthers form a ring round the style. In the irregular 

 corolla and the union of the anthers the Lobelia differs from the 

 other members of the Campanulaceae with which it is associated. 



The Pipewort (Eriocaulon septangulare) grows in certain dis- 

 tricts with the Water Lobelia. The root stock is creeping, and 

 bears on its under surface long, white fibrous roots, and at its 

 extremity grass-like leaves. The flowering stem rises above the 

 water, and is usually marked with seven raised lines, whence the 

 name " septangulare." The flowers are mottled white and black, 

 and arranged in a dense tuft, those in the centre being staminate, 

 those at the edge pistillate. The distribution of the plant is 

 limited in our islands to the Irish lakes, where it is often very 

 abundant, and to Skye and the neighbouring islands. 



THE VEGETATION OF STILL WATER : (a) PONDS AND LAKES. 

 Ponds are abundant in pastures, especially if there is a substratum 

 of clay. They are often found where two hedges at right angles 

 to each other join, and on the shady side of the hedge, for in such 

 a situation the cattle can get shelter from the noonday sun whilst 

 quenching their thirst. If the pond is not under the shelter of 

 the hedge it is generally planted round with Hawthorn, or Willow, 

 or some other shrub, gaps being left for the animals to gain easy 

 access to the water. In early spring a pond of this kind, with 

 the Hawthorn hedge just coming into bud, perhaps a Willow 

 bough overhanging, and the weeds just beginning to show their 

 green leaves on the surface of the pond side by side with some of 

 the old autumn ones that still float on it, makes a restful spot 

 in the monotony of the pasture. The Duckweed may cover 

 the whole surface, or only bits here and there near the edge ; 

 tangles of yellowish-green Algae, which have been engaged during 

 the winter in propagating themselves at the bottom of the pond 

 are now rising towards the surface to get as much light as possible 

 for the new growth which is to take place during the spring and 



