. Essentials of biology presented in problems. Biology. 86 ROOTS AND THEIR WORK Another experiment is the following: Divide the interior of a shallow wooden into two parts l\v an incomplete partition. Partly fill the box with sawdust and place the opening in the partition so that it is below the surface of the sawdust. Plant peas and beans in the sawdust on one side of the partition, water very shghtly, but keep the other side of the box well soaked. After two weeks, take up some of the seedlings and note the effect on the roots. Water a Factor which determines the Course taken by Roots.
. Essentials of biology presented in problems. Biology. 86 ROOTS AND THEIR WORK Another experiment is the following: Divide the interior of a shallow wooden into two parts l\v an incomplete partition. Partly fill the box with sawdust and place the opening in the partition so that it is below the surface of the sawdust. Plant peas and beans in the sawdust on one side of the partition, water very shghtly, but keep the other side of the box well soaked. After two weeks, take up some of the seedlings and note the effect on the roots. Water a Factor which determines the Course taken by Roots. — Water, as well as the force of gravity, has much to do with the direction taken by roots. Water is always found below the sur- face of the ground, but sometimes at a great depth. In order to obtain a supply of water, the roots of plants frequently spread out for very great distances. Most trees, and all grasses, have a greater area of surface exposed by the roots than by the branches. The mes- quite bush, a low-growing tree of the American and Mexican deserts, often sends roots downwards for a dis- tance of forty feet after v>-ater. The roots of alfalfa, a cloverlike plant used for hay in the Western states, often penetrate the soil after water for a distance of ten to twenty feet below the surface of the ground. Structure of a Taproot. — To understand fully the structure of the root, it will be necessary for us to examine some large, fleshy root (a taproot), so that we may get a little first-hand evidence as to its internal structure. If you cut open a parsnip or carrot so as to make a cross section of the root, you find two distinct areas — an outer portion, the cortex, and an inner part, the wood. If you cut another parsnip in lengthwise section, these structures show still. Dandelion plant. Note the length of the root. Photographed by Please note that these images are extracted from scanned page images that may have been digitally enhanced for readabili
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1911
