PHYSIOLOGY OF THE ROOT. 



the aerial roots are striking out from every part of the 

 main stem almost to its summit. 



153. THE BANIAN. But the most remarkable in- 

 stance of this habit is found in the Banian, or Indian 

 Fig of the East, fig. 14. This tree sends out long, 

 horizontal arms, and from these drop down the aerial 

 roots, lengthening until they reach the soil, where they 

 finally establish themselves, put forth other stems, and 

 send down other roots, until the parent tree, surrounded 

 by numerous trunks almost vying with itself, becomes a 

 grove, and thus the multiplication of trunks goes on in- 

 definitely. But the Banian tree can neither be described 

 nor delineated as it appears in life, with its expansive 

 canopy of branches a beautiful green temple of a thou- 

 sand pillars, curtained with the glossy clusters of its shin- 

 ing leaves. 



154. PARASITIC ROOTS. These are a variety of 

 aerial roots that shoot forth in the air ; but instead of 

 reaching the soil, they attach themselves to other plants, 

 from which they derive their nourishment. They may 

 be divided into two classes GREEN PARASITES, and 

 PALE or COLORED PARASITES. 



155. GREEN PARASITES are furnished with digestive 

 organs of their own, and are, in fact, not wholly parasitic, 

 because they perform, in their own tissues, a part of the 

 vital action necessary to their support. The Mistletoe 

 is an example. This shrub unites itself so perfectly 

 with the Foster-plant as to appear a natural branch. 

 Creeping and twining parasites abound in tropical forests, 

 where they often crush to death the trees which they 

 enfold. 



156. PALE PARASITES have no green foliage, and 

 consequently no digestive apparatus. Hence they must 

 live entirely at the expense of the Foster-plant. This 

 will be better understood when you become acquainted 

 with the functions of the Leaf. The English Dodder, 

 Plate VII. fig. 3, is a pale parasite, and is well repre- 

 sented, showing the suckers at the end of the stalk, by 

 which it adheres to the herbs, on whose elaborated juices 

 it feeds and grows. Our common Dodder is a beautiful 

 little plant, notwithstanding its habit. Its profuse 

 clusters of white flowers look as if they were strung 

 together with numerous threads of gold-colored silk. 

 The clustered flowers of Beech-drops, and the curious 

 Indian Pipes (Monotropa), which are parasitic on the 

 roots of old trees, or among decaying herbage, belong to 

 this class. The Monotropa, in its whole substance 

 leaf, stem and flower when fresh, has the appearance of 

 pure white wax. The leaves are reduced to mere scales, 



Parasitic KooU. What varieties? How distinguished? Which perfect 



and the close resemblance which its shape bears to a 

 tobacco pipe has suggested the name. 



157. ONE-FLOWERED PARASITES. Sometimes the 

 parasite is reduced to a single flower, seated directly on 

 the Foster-plant. Such is the Rafflesia, fig. 2. This, 

 although a parasite, is the largest flower known. It is 

 truly the Mastodon of Flowers. It measures from eight 

 to ten feet in circumference, and weighs fifteen pounds ; 

 while the cup in the centre will contain eight quarts, 

 English measure. This flower is of a brick-red, inclining 

 to orange, marked with white spots. It is parasitic on a 

 species of Grape-vine, and is found in Sumatra. 



158. EPIPHYTIC ROOTS. These are useful merely in 

 their mechanical support. The root-like processes by 

 which the Ivy ascends, and the Trumpet vine sustains 

 itself in the air, are properly epiphytic, though they are 

 not usually called so ; and this is true of all root-like 

 processes which serve merely for mechanical support. 



159. AIR PLANTS. But epiphytic roots chiefly dis- 

 tinguish a peculiar class of plants that are called 

 EPIPHYTES, because they grow on other plants, and AIR- 

 PLANTS, because they derive their nourishment from the 

 atmosphere. They generally grow on the trunks and 

 branches of trees, to which the epiphytic roots adhere 

 merely for support, their true roots being free, and hang- 

 ing loose in the air. Many of the tropical Orchids are 

 of this kind. They are greatly prized by Florists, not 

 only for their beauty, but for their fantastic varieties 

 of form and color, which give them a wonderful likeness 

 to butterflies, and other bright-hued insects. One of 

 their forms may be seen at fig. 1, and also their free 

 roots shooting out into the air. The Tillandsia, or 

 long Gray Moss that grows so profusely on the Live- 

 Oak, Ccttonwood, and other trees of the South, is a plant 

 of this kind. 



160. VEGETABLE PHYSIOLOGY is that branch of the 

 science, which comprehends a knowledge and observation 

 of the organic machinery, as endowed with life, and 

 manifest in action. It relates chiefly to VITAL HABITS 



AND FUNCTION. 



CHAPTER XIII. 



PHYSIOLOGY OF THE BOOT. 



161. THIS organ does not, like the stem, grow by 

 an extension of its whole length, but by the extremities 

 alone, as you have already been apprised (129) ; and this 

 mode of growth is well adapted to the circumstances 



parasites? Why? Instances of Green Parasites. Palo Parasites. One-flowered 

 parasites. Describe Epiphytic Boots. Air plants Instances. 



