90 COMMUNAL LIFE OF ORGANISMS sect, ii 



however, met with on the ground, especially in the forest, where all kinds 

 of fallen fragments (withered leaves, twigs, flowers, and fruits) accumulate 

 year after year and produce humus. Saprophytes are therefore bound 

 up with other plants, but the bond is different from that associated with 

 parasitism ; for it is the cast-off parts and redundant individual plants 

 that they utilize. Some saprophytes select special kinds of vegetable 

 remnants and are therefore inseparably associated with definite species 

 of plants ; others are less narrow in their choice. Clavaria abietina, 

 Lactarius deliciosus, and certain other fungi are only met with in coni- 

 ferous forest, others select dicotylous forest, while others again grow 

 only upon dung, as is the case with Poronia, Coprinus, Pilobolus, and 

 Sordaria among Fungi, and Splachnum among mosses. 



Among cryptogamic and phanerogamic plants alike, saprophytes 

 display a very varied degree of adaptation to the saprophytic mode of 

 existence.^ Every kind of humus is permeated with fungal mycelia 

 and bacteria, and the soil in forest at autumn reveals hosts of pileate 

 fungi. Phanerogamic plants that are most completely adapted to a 

 saprophytic life, that is to say, holosaprophytes, exhibit the following 

 characters : 



1. They have little or no chlorophyll, being yellow, red, or brown in 

 tint. 



2. Their leaves are upwardly directed, and more or less reduced to 

 adpressed scales. 



3. Stomata are usually absent. 



4. The root-system is more or less reduced, some forms like Corallo- 

 rrhiza being quite rootless ; the roots are short, thick, and but feebly 

 branched, and in the vast majority of cases form mycorhiza. 



5. The vascular bundles are reduced. 



As examples may be cited : Neottia, Corallorrhiza, Epipogum, Pogo- 

 nopsis, and other orchids ; some Burmanniaceae ; Triuridaceae ; Mono- 

 tropa and Sarcodes among Pyrolaceae ; Voyria in the Gentianaceae.^ 



Hemisaprophytes have the external appearance and structure of 

 normal plants that assimilate carbon dioxide. Their needs as regards 

 organic nutriment probably differ extremely, for while some cannot 

 exist away from a soil rich in humus, such as a forest soil, others, like 

 many orchids and species of Pyrola, are tentatively to be regarded as 

 facultative saprophytes.^ 



LIANES 



While the want of humus-containing food constitutes the bond uniting 

 saprophytes with other plants, lianes are linked with fellow plants by 

 reason of the want of support for their weak long- jointed stems by which 

 they reach the light. The term liane is here employed in the widest 

 sense, and includes twining plants as well as the various kinds of other 

 chmbers. Lianes owe their origin to the grouping of plants into com- 

 munities in the form of forest and bush ; the shade due to dense vegetation 

 has caused them in the past to elongate, to produce long intemodes, 

 and in the course of time to adapt themselves in various ways not only 



^ See p. 85. " See Johow, 1885, 1889 ; Percy Groom, 1895 a and b. 



" See Heinricher, E., 1896, 1897, 190 1-3 ; Wettstein, R. v., 1902. 



