124 



BRITISH PLANTS 



about destructive changes of any kind in organic matter. 

 All plants, green or not, if supplied with sugar and the 

 proper mineral salts, can build up proteins, so there is 

 no reason why the proteins required by saprophytes for 

 then: nutrition should be obtained in the same way as 

 the carbohydrates. Saprophytes, as a rule, make their 

 own proteins, but most of the nitrogen required is ab- 

 sorbed in the form of ammonium-compounds, in which 

 humus is richer than in nitrates. At the same time, there 

 is little doubt that proteins, if present, are also absorbed 

 and utilized in the economy of the plant. 



(i.) Total Saprophytes. There are very few total 

 saprophytes among the higher flowering plants in this 

 country, and a curious feature in 

 them all is that they do not absorb 

 the products of decay from the 

 humus directly, but through the 

 intervention of a mycorhiza, a sub- 

 ject-fungus which inhabits the roots 

 or stems, and replaces the root-hairs 

 of the higher plant (Fig. 39). The 

 British flowering saprophytes are : 



Neottia Nidus-avis, the bird's-nest 

 orchid, a leafless saprophyte, fre- 

 quently occurring in the humus of 

 moist woods, especially under old 

 beeches and in hazel- copses. 



Monotropa Hypopitys, the yellow 

 bird's-nest, a saprophyte with scaly 

 leaves found occasionally in the 

 humus of fir, beech, and birch woods. 

 Corallorhiza innata, the coral-root, a very rare sapro- 

 phytic orchid found in boggy woods. It has a much- 

 branched fleshy rhizome, but no roots (Fig. 40). 



Epipogum aphyllum, a yellow orchidaceous plant, 

 possessing neither leaves nor roots. It has been found 

 only once in this country. 



Saprophytes are all descended from green ancestors, 

 but owing to their mode of life the presence of chlorophyll 

 is rendered unnecessary, and it has disappeared ; the 

 leaves, not being required for purposes of nutrition, have 

 degenerated into scales t or vanished altogether. The 

 chief factor in their degeneration has, no doubt, been the 



FIG. 39. APEX OF A 

 ROOT INVESTED WITH 

 A MYCORHIZA. (MAG- 

 NIFIED.) 



