28 Commercial Gardening 



Other plants of dry countries produce hard and wiry leaves, like the 

 Grass tree of Australia (Xanthorrhoea), and must likewise be kept on the 

 dry side during winter. The Rushes (Juncus) of our marshes and river 

 banks belong to the same family, but their stems are very largely made 

 up of loose, spongy tissue, surrounded by a thin layer of more solid 

 structure, almost like a skin. They are therefore capable of giving off 

 large quantities of water at any time when circumstances require it. 

 Some plants of dry climates and arid soils and situations clothe themselves 

 with a more or less dense coating of hairs; and in proportion to the density 

 of this covering must they be kept dry in winter, otherwise they would 

 sooner or later get into an unhealthy condition and ultimately perish. The 

 roots are usually the first to suffer from an excess of moisture, but the 

 functions of the leaves and other parts also get deranged. The common 

 Stock, in a wild state, inhabits dry chalk cliffs, and all parts of the stems, 

 leaves and calyx are densely covered with star -shaped, branching hairs. 

 Seedlings under cultivation are extremely liable to damp off while quite 

 young, if kept too close and moist in the seed pans or boxes. The exces- 

 sive moisture renders them liable to attack by the " damping-off" fungus 

 (Pythium debaryanum). It is not usually regarded as a desert plant, but 

 it serves to explain a similar difficulty when brought under cultivation 

 from its dry, wild habitats. 



Clammy-leaved Plants. At first sight these may not seem peculiar, 

 when Petunias and Salpiglossis are mentioned, for there are many other 

 examples under cultivation. They are plants, however, which delight in 

 sunshine and flower best in dry weather. The writer has seen Pelar- 

 goniums and other plants remain stunted and lose their foliage in a dry 

 garden on the chalk formation, in a droughty summer, while Petunias, 

 Gaillardias, and other clammy-leaved plants were the only flowering sub- 

 jects in the beds. While young and making growth they enjoy fairly 

 liberal watering, with a moist atmosphere, but to bloom freely they must 

 have plenty of light and air, and be kept dry overhead. The viscid hairs 

 with which they are covered enable them to recuperate themselves during 

 the night from the deposit of dew in the open ground. 



Insectivorous Plants. Many plants, whose root system is not well 

 developed, or which live in swampy places, where they have difficulty 

 in procuring a sufficiency of nitrogen in the usual way, have evolved 

 some peculiar contrivances for eking out the supply. The Sundews 

 (Drosera), Venus Fly-trap (Dionasa), Pitcher Plants (Nepenthes), (fig. 41). 

 Butterworts (Pinguicula), and Bladderworts (Utricularia), belong to this 

 class, and many of them are cultivated. By various means they manage 

 to capture and detain insects and other small creatures, which they 

 digest or dissolve, absorbing the nitrogen. The Sundew (fig. 11) 

 develops on the upper surface of its leaves numerous tentacles, each 

 terminated by a sticky gland. Flies alighting upon a leaf get held fast 

 by the viscid matter, while the other tentacles close upon their victim. 

 The protoplasm now forms a " ferment", and the liquid is spread over the 



