452 NEW JERSEY AGRICULTURAL COLLEGE 



The seeds of the dodder are not far from the size of those of red 

 clover, and might be mistaken for alfalfa seed or even that of timothy. 

 To show the relative size of the seeds of different species of dodder 

 and some of the commercial seeds among which the dodder is carried 

 as foul stuff, the engraving (Plate XIL) has been prepared where the 

 seeds are shown in groups alternating with groups of seeds of standard 

 forage crops. 



A study was made of the germination of the dodder seeds. 



The dodder root is the first portion to leave the seed-coats in ger- 

 mination, is colorless, and, while variable with the species and size of 

 seed, near a third of an inch in length. It is distinguished from the 

 stem by its somewhat greater size, absence of the yellowish-green 

 that comes in the seedling when growing in full sunlight, and in its 

 lower portion is covered with short root-hairs. These hairs are 

 scarcely more than in name, being only papilhe upon the surface,, 

 arising from the middle of each surface cell in the area for a short 

 distance back from the tip. In some roots the hairs come down to 

 the tip, there being no root-cap and the end consisting of several cells 

 of nearly equal length. The root grows very little in length as the 

 plant elongates, and when the stem is two inches long, the root, then 

 a third of an inch in length, is fully grown. The tip of the root is 

 practically the same in structure, whether growing in water, sand or 

 rich soil, with light or darkness. The normal position of the germi- 

 nating plantlet is, with its root-tip, only slightly buried in the soil and 

 extending upward, forming a "loop" in the stem, just above the root, 

 the seed-coats, with the large supply of endosperm, still in the soil. 

 As the growth advances the "loop" increases in size, the end of the- 

 stem finally becoming separated from the seed-coats and being lifted 

 up free in the air, still with a "loop" near the end. After about 

 ten days the slender wire-like stem becomes straight and the active 

 nutrition begins. 



All this time the root end has remained comparatively unchanged, 

 fastened by the root-hairs to the soil, from which it imbibes water. 

 The short, stout hairs are particularly interesting in presenting a 

 movement of the protoplasm, that can be readily seen with a one- 

 sixth objective, the flow being along the inner wall of the papilla. 

 Under similar circumstances, ordinary seeds, like those of clover, will 

 produce a long, slender root, penetrating deeply into the earth, 

 showing an evident cap at the end, upon which no root-hairs appear 

 until some distance back from the cap, and then they form as slender 

 threads, that are very many times their diameter in length and of. 



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