SCIENTIFIC AGRICULTURE 



January, 1921. 



Figure 3. — Heaving of Alfalfa in Spring. The crown of the 



plants with single tap-roots are pushed out several 



inches above the surface of the soil. 



root were practically all heaved out of the soil, some 

 having their roots lifted and expased above the sur 

 face of the ground for over four inches whilst those 

 few plants having branched roots were so firmly 

 anchored that they had suffered comparatively little 

 from .heaving. 



It may be pointed out that the heaving of the tap- 

 rooted plants was not owing to any shallowness of 

 tihe roots, as after the thaw, it was ea-sily possible to 

 draw out plants with roots two feet in length. On 

 the other hand, it was alma-t iinpos-sible to draw the 

 plants wjiich had branching root.s, and in the at- 

 tempt the stems were usually broken off near the 

 surface of the soil without dislodging the roots. 



In the course of observations made at a later date 

 on mature three^year-oldl ]ilants. specimenisl were 

 found, which, in addition to having the branching 

 root sy.slem referred to above, had the |)roperty of 

 producing lateral Inids from t^ie rootstock wiiieli sub- 

 sequently developed into rooting underground stems 

 or true rhizomes. 



These are classified as type B. 



Type B. — In this type, the buds which give rise to 

 the underground stems ai-e produced at the ba.se of 

 tlie crown just underneath the surface of the soil, 

 and apparently are formed iiiainh' in latter \nirt of 

 summer and early autumn. 



As the buds develop, the shoots produced take an 

 oblicpie doM-nward course iiit'i the soil and continue 

 to grow in this direction during the autumn until 

 land is frozen hard and growth ceases. 



If the land is fairly dry and the soil is not dis- 

 turbed, these white and apparently tender shoots do 

 not appear to suffer from hard frasts, and when 

 growth commences in the toll(i«-ing sprii".;-. the grow- 

 ing tip of the underground stem gradually cuiwes 

 upwards towards the surface of tihe soil and even- 

 tually emerges above ground sometimes from six to 

 nine inches distant from the jioint of contact with 

 the parent crown. 



The young stem continues to grow, and rapidly 

 develops into a true aerial stem producing foliage 

 and flowers like the parent, and ha.s all tjie appear- 

 ances of being a distinct plant. 



If we examine the part of the stem undergi-ound. 

 fine, fibrous roots will be found arising from the 

 under-.surface ; thus forming a \^■"ll-defined rhixome 

 capable of developing into a distinct plant and hav- 

 ing the power of maintaining a separate existence 

 and quite independent of the iiarent crown. 



From this explanation, it will be seen that if the 

 main crown of the plant should die from injory or 

 other cause, the life of the plant may be continued 

 by the young plants formed from the fully devel- 

 oped rhizomes. 



Hence, it will be readily understood that old Al- 

 falfa plants having the power of producing root- 

 ing underground stems will have the ability to reno- 

 vate themselves by the jiroduction of a new crop of 

 young plants, and for t.iiis reason will be much more 

 resistant either to winter frosts, competition with 

 other plants, or to injury h>- the grazing or treading 

 of cattle, and will conse([uently, under normal con- 

 dition.s, maintain a good stand for many years. 



Type C. — 111 the autumn of 1912 whilst examin- 

 ing the rooting habits of yellow flowered Alfalfa 

 (Medicago falcata) a type of root was found, which 

 differed veiy materially from any of the forms 

 already described under tj'pes A and B. 



This fonn seems to correspond very clo.sely with 

 those found by Oakley and Carver in 1912 and 

 described by tvliem in a bulletin published in 1913. 



During the course of our inspection, several plants 

 were found on which buds and aerial stems were 

 produced on the true roots. In some cases, stems 

 were found arising from roots at points six to eight 

 inches below the surface of the soil. 



In this type, the root system as a whole may be 

 considered a.s being made up of branched roots, some 

 of which penetrate the .soil in a vertical manner ami 

 from wthich strong lateral branches are given off. 



These lateral roots frequently arise from the main 

 root at a point several inches below the surface of 

 the soil, and may travel for long distances in an 

 almost horizontal direction. 



Xear the point where the laterals leave l;iie main 

 root, the lateral may be comparatively thin; but 

 further away, thickened areas freciuently occur. In 

 some eases, the thickening is quite irregular, in 

 others it is of a fairly regular spindle-shaped fonn. 



On some of these spindle-shajied swellings, buds 

 are produced, wliicji develop forming the aerial 

 Lshoots, and from the same swelling, a root system 

 is produced similar to that of the parent plant. 



The spindle-like thickenings are not confined 

 simply to the lateral roots: but are likewise found 

 on those growing in a vertical direction. 





Fiig:ure 4. — Root System — Type B. Crowti of an olfl plant wliiiti 



has been renewed by the development of nndergromui 



stems from the parent crown. 



