Novembtn-. 1921 



.SC'l KXTIFIC AtUUCULTUKIO 



79 



Variation and Inheritance in Red Clover 



By M. 0. MALTE, Ph. D., 

 Doniiiiioii Agrostologist, Central Experimental Farm, Ottawa. 



lied clover (Tri folium pratense L.) is, as 

 is well known, an extremely variable plant. 

 In other words, it constitutes a species 

 made np of an exceedingly large number 

 of different morphological and biological 

 types. It presents accordingly a very rich 

 field for investigators and particularly for 

 those interested in research work bearing 

 on heredity and kindred subjects. Under 

 the circunLstances it is only natural that a 

 large number of scientists have interested 

 themselves in the study of its peculiarities, 

 especially in reference to variation and in- 

 heritance of cjiaraeters. 



As much of the information gained has 

 been published in languages which are not 

 understood by the majority of Canadian 

 agriculturists,- the writer has endeavored 

 to bring together in a brief synoptical form 

 the most outstanding results of the prin- 

 cipal investigations on Red clover, under- 

 taken in Europe as well as on this conti- 

 nent, giving also a list of the principal 

 literature on the subject. The writer does 

 not claim that the said list is complete ; 

 in fact, the writer is aware that several 

 other papers dealing with inheritance in 

 Red clover exist, but as they are not acces- 

 sible to the writer, reference to them has 

 been omitted. Several lines of investiga- 

 tions have also been touched upon, for in- 

 stance investigations carried out at tihe 

 Central Experimental Farm, Ottawa, Ont., 

 bearing on the rather complicated relations 

 between winter-hardiness and perennial- 

 ism, the reason being that the investigations 

 in question are not yet completed. 



I. POLLINATION & FERTILIZATION. 



The question of w^hether red clover can 

 be successfully self-fertilized or not has 

 long been a subject of investigation, the 

 impetus being given by Darwin Avho found 

 that red clover heads protected from visits 

 of bumble bees did not produce a single 

 seed. This discovery of Darwin's has by 

 some authors been construed to mean that 

 Darwin found that red clover is self -sterile, 

 i.e. that a red clover plant is unable to 



produce seed if pollinated by its own pol- 

 len. Such a conclusion can, however, hard- 

 ly be drawn from Darwin's own account 

 which reads as follows {Darwin 1, p. 71) :* 

 "From experiments which I have 

 lately tried, I have found that the 

 visits of bees are necessary for the 

 fertilization of some kinds of clover ; 

 for instance, 20 heads of Dutch clover 

 {Trifolium repens) yielded 2,290 seeds, 

 but 20 other ^leads protected from bees 

 produced not one; again, 100 heads 

 of red clover (Trifolium pratense) 

 produced 2,700 seeds, but the same 

 number of protected heads produced 

 not a single seed." 

 Darwin obviously means that in the ab- 

 sence of a pollinating agency the forma- 

 tion and the maturing of seed do not take 

 place ; he does not say that self-pollination 

 is ineffective. 



De Vries (I, p. 939) also found that in 

 the absence of insects red clover refused 

 to set seed. He went, however, a step 

 farther and found that, when red clover 

 flowers were artificially self-pollinated, no 

 seed was obtained. Accordingly, de Vries 

 concluded that red clover in all probability 

 is self-sterile. 



Stehler a7id Schroter (I, p. 73) expres- 

 sed a similar opinion in 1883 and later 

 qualified the same by stating that Red 

 clover is self-sterile. Sirrine (I, p. S9-90) 

 also came to the conclusion that Red clover 

 is self -sterile and so did Witte (I, p. 336). 

 Witte carried out quite extensive experi- 

 ments during the years 1905-1908. A to- 

 tal of 79 experiments were undertaken 

 wit;fi red clover plants of different origin. 

 In 21 of the experiments the object was 

 to ascertain the effect of pollen on the 

 pistils of the flowers of the same plant, 

 in other words to determine whether red 

 clover is self -sterile or not. All heads used 

 were satisfactorily isolated and numerous 

 crosses made between flowers of the same 



* The literature quoted will be given at the 

 end of Part 3. in the January issue. 



