SKETCH OF THE RUDIMENTS OF BOTANY 



ELEMENTARY ORGANS. 



1. The tissue of which plants consist, appears under four forms, viz : cel- 

 lular tissue, woody fibre, vascular tissue, and ducts. These are called ele- 

 mentary organs. 



2. Cellular tissue or parenchyma is composed of transparent vesicles, 

 variously cohering with each other. It is the only form universally found 

 in plants ; the other forms being often partially or entirely wanting. 



3. Woody fibre is a tissue consisting of elongated tubes, similar to the 

 vesicles of cellular tissue, and is therefore often called, elongated cellular 

 tissue. 



4. Vascular tissue, of which the spiral vessels are usually taken as the 

 type, consists of tubes of variable length, with delicate walls, to the inside 

 of which a spirally coiled fibre adheres, capable of being unrolled. It en- 

 ters into the composition of all plants of higher organization, (all above the 

 mosses.) 



5. Ducts are elongated, transparent tubes, composed of tissue that is not 

 capable of being unrolled. 



6. All these forms are covered by a membrane called the epidermis or 

 cuticle. 



7. From pecuUar combinations of the elementary organs are formed the 

 compound organs. 



8. The root is formed by the descending and dividing fibres of the stem ; 

 and by it plants are with few exceptions fixed to the earth, and supplied 

 with a portion of their nourishment. 



d^ It is distinguished from the stem by the absence of leaves, of pith even 

 in those plants in which it is abundant in the stem, and of spiral vessels. 



10. It usually consists of three parts; th.e7ieck, (colhim) or line of separa- 

 tion from the stem ; the body or middle portion ; and the fibres or httle roots, 

 through wliich the nourishment is principally derived. 



11. The following are the principal kinds of roots : 



a. Conical, or principal tap root, as it is sometimes called ; tapering down- 

 wards and emitting fibres from various parts of its surface ; as in the 

 Carrot. 



b. Fusiform, when the conical root is attenuated towards the neck, as 

 well as below ; as in the Radish. 



c. Napiform, when it is swollen out extremely in the upper part and sud- 

 denly attenuated below ; as in the Turnip, 



