STRUCTURE OF PLANTS. 



hand, and those of the useful plants on the other, man is enabled to select the materials 

 proper to be used in accordance with his varying needs. It is easy to eat too much of plants 

 that contain sulphur, lime, phosphorous, fatty, carbonaceous matter, or any other of the 

 chemical ingredients of plants, when the system may really demand the use of those 

 endowed with quite different properties; hence the value of this knowledge. 



It is truly wonderful that an order of plants, containing perhaps several hundred 

 genera and many thousand species, will maintain, throughout all their variety of form and 

 color, a predominance of one or more chemical elements. For instance, the Cruciferae, or 

 Mustard family, one of great utility to man, every member of which affords nutritious 

 and medicinal benefits, principally anti-scorbutic, or scurvy-destroying, in character. 

 Thev all contain nitrogen and sulphiu" more largely than other plants, which accounts for 

 their yielding ammonia when undergoing decay, as well as for their blood-purifying prop- 

 erties. Many of our familiar table condiments, as mustard, horseradish, cress, etc., belong 

 to this order. The Crucifera are natives of the temperate zone, and are a natural antidote 

 for the excessive use of fat-producing matters, so common in those regions. 



The order LeguminosEe is perhaps the largest of all, and is remarkable tor containing 

 lime, albumen and starch. Its value in the animal economy is great, as it furnishes the 

 bone and sinew, which constitute the essential framework of the animal structure. Like 

 tile other useful plants, they are found everywhere, to meet the necessities of uni\ersal 

 animal life, while the poisonous or dangerous plants are confined to a very limited range. 

 The LeguminossB are also possessed of many well-known medicinal properties, whose 

 \alue can scarcely be overestimated. Plants yield about thirty-four different products, 

 such as resin, oil, wax, gluten, starch, sugar, etc.; and at least eight well-known acids, 

 viz. : oxalic in rhubarb, tartaric in grapes, citric in lemons, malic in apples, gallic in 

 oak, benzoic in balsam, prussic or hydi-ocyanic in almonds, and phosphoric in oats. 



Vegetable chemistry, as may be conjectured from the remarks already made, is much 

 too extensive a subject to receive proper attention in a subsidiary paragraph of a popular 

 work devoted mainly to the poetry and cultivation of flowers; but this much it has been 

 thought desirable to insert as a slight hint on an important subject, and a stimulus to 

 further investigation. 



For the more easv comprehension of the general principles of botany by tile unsci- 

 entific lover of flowers, it is now proposed to consider the individual plant under the various 

 relations of its internal structure, and its component parts viewed externally, together with 

 the more important subdivisions of these, in a natural sequence, and in as few words as 

 possible. What plants are composed of becomes then the next subject for consideration. 



TISSUES. 



Plants are made iiji of innumerable minute sacs, called cells, and generally of a lot 

 of tubes or vessels, which were also originally rows of these cells, the whole constituting 

 the material substance of plants, or what is technically known as tissue. The nourishment 

 of plants passes from cell to cell through the thin membranes that constitute the cell walls. 

 These cells are of a definite structure, as found by microscopic observation, and the tissues 

 are of different kinds according to the structure and arrangement of the cells and tubes. j \ 



