802 



GARDENERS' CHRONICLE 



them many times. There are, however, a large number of 

 colorless flowering plants that, like saprophytes, seem to 

 require nearly pure humus for their growth and are never 

 found except in localities where rotting leaves are abun- 

 dant. It is now thought that such plants have formed a 

 partnership, or symbiosis, with various fungi, or that, as 

 in the case of the Indian pipe, they are actually parasitic 

 upon it: It is well-known that many flowering plants 

 have roots infested with fungus which they do not seem 

 able to get along well without. In true symbiosis, each 

 partner is supposed to contribute something toward the 

 common good. In the present case, since the flowering 

 plant does not produce root hairs, it is conjectured that 

 fungi supply the place of these and perhaps digest certain 

 substances in the soil for the use of both partners. Many 

 fungi, however, are known which are able to absorb 

 sugars and starches from decaying leaves and do not. 

 therefore, require association with other plants. The 

 union of these w-ith a flowering plant has every appear- 

 ance of being a case of parasitism on the part of the 

 higher plant. 



A still more curious union of this kind is found in the 

 prothallitim or gametophyte of many fernworts. which 

 are not only colorless but subterranean. So rare are the 

 prothallia of the club-mosses that those of many species 

 have never been seen. All such prothallia must be either 

 parasites or saprophytes. Possibly it may be nearer the 

 truth to say that they are half-parasites, half-saprophytes. 



There is probably no class of plants in the world more 

 useful than the saprophytes. It is true we do not make 

 use of many of them directly, and food plants are of more 

 immediate value, but if it were not for the saprophytes 

 to remove the dead parts of plants by decay, the ground 

 would long ago have become so encumbered with dead 

 vegetation that there would be no room for the food plants 

 to grow. It was once pretty well accepted that the fun- 

 gus saproi>hytes are derived from degenerate algas, but 

 a good many botanists now hold that fungi have existed 

 since the beginning and have assumed their various forms 

 through evolution exactly as green plants have done. 



In the [jopular mind, still another grouj) of plants are 

 often confused with parasites. These are the epiphytes 

 which. like the others, live upon other plants, but difl^er 

 in using them onlv for support. In tropical regions where 

 moisture, warmth, and light are most abundant the press 

 of plants is so great that there is no longer room for all 

 on the ground, even if the tall and dense forests favored 

 by such conditions allowed sufficient light for growth 

 to penetrate to the ground below. The soil is thickly 

 covereil with plants that can endure the shade but the 

 herbaceous sjiecies that require more light are obliged to 

 secure locations on the branches of trees or perish. Such 

 forms are often given the very descriptive name of "perch- 

 ing plants'' since they use the larger plants for support. 

 Although epiphytes have their highest development in 

 the tropics, there are a few even in temperate regions, 

 but they are pretty generally low forms of life such as 

 mosses, liverworts and lichens, which can endure con- 

 siderable cold and drought. 



Epiphytes are often spoken of as "air plants" and many 

 people suppose that there is a single species entitled to 

 be called bv this name, which lives upon air in a manner 

 different from other plants. Epiphytes, however, are no 

 exception to the rule among green plants and require the 

 same food materials. The problem they have solved in 

 beconu'ng epiphytes is simply how to get the required ele- 

 ments in tb.e places they inhabit. Of the elements likely 

 to fluctuate in amount, water is the most important. 

 Epiphytes, therefore, seldom occur except in regions of 

 abundant rainfall. Even here short seasons of drought 



are likely to occur and in consequence we find many 

 devices for securing water while it is to be had and stor- 

 ing it up against a time of need. Some kinds of pitcher- 

 plants store water in the pitchers and many members of 

 the pineapple family have leaves with clasping bases in 

 the hollows of which little cisterns of water accumulate. 

 In such cisterns, at least one little insect-catching water- 

 plant — a species of bladderwort (Utriciilafia Huiiiboldtii) 

 — finds a home and thus becomes an epiphyte upon an 

 epiphyte. A large number of orchids have curiously modi- 

 fied stems, called pseudobulbs in which water is stored, 

 while some of the sword ferns have little bladder-like 

 tubers upon the rootstocks that contain water. 



Among epiphytes, species having a thick epidermis, or 

 covered with hairs and scales, are the rule. Species with 

 thin leaves usually have some provision for dropping 

 them in seasons of long-continued di'ought, only the fleshy 

 rootstocks remaining alive. A large number of orchids 

 have roots with a highly specialized cortex which acts like 

 a sponge in soaking up water when it rains, and some of 

 these have the added faculty of absorbing moisture from 

 the air between showers. Such roots produce no root- 

 hairs, nor do they attempt to attach the plant to its sup- 

 port. Instead they hang down in clusters and act simply 

 as absorbing organs. Other plants may begin life as 

 true epiphytes but in course of time they send down long 

 roots that finally penetrate the soil and supply some of 

 the food materials. Such plants then become half-epi- 

 phytes. True epiphytes obtain their mineral matter from 

 the dust washed down by rains, from the decaying leaves 

 that may find lodgement among the roots and from the 

 bark of the tree to which they are attached and into which 

 some of their rootlets may penetrate. 



Most epiphytes have devised special forms of roots for 

 retaining their hold upon their supports. The main roots 

 may be flattened and. clinging close to the bark, give oft' 

 great numbers of processes like root-hairs, which unlike 

 these organs in other plants are rather permanent in char- 

 acter and function as holdfasts instead of absorbing- 

 organs. The roots of epiphytic ferns are often thickly 

 clothed with these brownish, root-like organs that cling 

 so closely to the bark that it is much easier to tear oft 

 bits of the bark than to loosen the roots when collecting 

 the plants. 



The principal tropical epiphytes belong to the orchid. 

 fern, club-moss and pineapple families. Nearly three 

 hundred species of wild pines, as the plants of the last 

 mentioned family are called, are found epiphytic in the 

 tropics. One species, the so-called gray or Spanish moss, 

 is found on trees in the warmer parts of the United States. 

 Among other tro])ical epiphytes are species of figs, pep- 

 pers, and cacti. Some epiphytes are quite inconspicuous 

 and are almost hidden by the mosses that share their 

 habitats with them, but the great majority compare very 

 favorabh- in stature with terrestrial plants. In favorable 

 situations they often crowd the trees in immense num- 

 ])ers — thousands on a sinele tree. 



Blow, bugles of battle, the marches of peace; 

 East, west, north, and south let the long quarrel cease ; 

 Sing the song of great joy that angels began. 

 Sing of .glory to God and of good will to man ! 



Hark ! Joining in chorus 

 The heavens bend o'er us ! 



The dark night is ending and dawn has begun ; 



Rise, hope of the ages, arise like the sun, 



All speech flow to music, all hearts beat as one ! 



John Greenle.^f Whittier. 



