NOMENCLATURE OF THE ROOT. 45 



roots. These are, their situation, direction, duration, 

 substance, form, and composition. 



3. Situation: By the situation is meant the soil or 

 place to which they are affixed ; and hence, they are said 

 to be subterraneous, aerial, floating, or parasitical. 



a. Subterraneous when they are in the ground, as with the 

 snow-drop and most plants. 



b. JErial when they are neither attached to the ground nor any 

 other substitute, but suspended in the air, as with the Indian fig and 

 srial flower. 



c. Floating when the root has germinated in the soil, separates 

 and floats upon the surface of the water, as with the common duck- 

 weed. 



d. Parasitical when they are attached to the bark of other living 

 plants, as with the misletoe. 



4. Direction: The direction is the particular posi- 

 tion in which roots grow ; so that they are called either 

 perpendicular, horizontal, or oblique. 



a. Perpendicular when the caudex or main body of the root de- 

 scends perpendicularly into the ground, as in most trees. 



b. Horizontal when the extension is nearly parallel to the plane 

 of the horizon, so that the roots form nearly a triangle with the stem 

 or herbaceous part of the plant, as in winter-green and sweet-flag. 



c. Oblique when the root takes an intermediate direction of the 

 perpendicular and horizontal. 



5. Duration : From the duration or length of time 

 which roots live, they are either annual, biennial, or 

 perennial. 



a. Annual those which are produced from seed, grow to their full 

 extent, and die in one year or season, as with barley, wheat, com- 

 mon pea, and garden bean. 



