so 



SC TEXTIFIC AGRIClI/rrRF. 



November. 1921 



heads and also between flowers from dif- 

 ferent heads of the same plant. Not a 

 .single jrerminable seed was obtained in 

 either case. That the pollination met.hod 

 used was quite .satisfactory was established 

 by the faet that, when it was employed in 

 crossing flowers belonginpr to two different 

 plants, well developed terminable seed was 

 olitained. Witte accordingly concludes 

 that red clover is iierfectly self-sterile, 

 i.e., that a red clover plant can not produce 

 germinable .seed nnless it is fertilized by 

 pollen fioni another individual. 



Experimenis cai-ried out by //. .V. V rand- 

 sen (Linhard, I. p. 720) in 'l910 and 1911 

 gave as results that when flowers of tihe 

 same heads were inter-pollinated only two 

 seeds were obtained from a total of 2,540 

 flowers, and that, when t;he flowers were 

 fertilized by pollen from other heads of 

 the same plant a total of 18 seeds were 

 secnred from 2,943 flowers, while cross- 

 pollination of heads of different plants 

 resulted in the yield of 959 seeds out of a 

 total of 2,180 flowers. From these results 

 Linhard concludes that from a seed grow- 

 er's point of view the red clover is self- 

 stei-ile. 



Similar results were obtained by Gnielin 

 (I) who worked with isolated plants pol- 

 linated by l)urable bees which, before being 

 let into the isolation cages, were examined 

 and found free from pollen from t'pe out- 

 side, and also by Westgate and Cor and 

 associated investigators (I, pp. 16-17). The 

 latter found, as a result of experiments 

 conducted in 1911 and 1912, that when 

 flowers of a head were inter-pollinated, 

 an average of 0.16 and 0.09 seed per head 

 were developed in 1911 and 1912 respec- 

 tively. Flowers pollinated with pollen from 

 another head on the same primary branch 

 did not L'ive a single seed and, wdien flow- 

 ers were pollinated with pollen from a head 

 on a different primary branch of the same 

 l)lant. only one seed from a total of 200 

 flowers was produced. Cross-pollination 

 l)etween different plants yielded an aver- 

 age of 14.3 seeds per head. From the ex- 

 periments Wcshjate and Coe and associat- 

 ed investigators conclude tpat the red 

 clover "is practically .self-sterile and that 

 pollen must come from a separate plant 

 i„ order to effect fertilization". 



On the other hand, some investigators 

 claim that isolated and self-pollinized rcil 

 clover plants may produce seed more or 

 less abundantly. Thus Meehan (1), after 

 a study of the flowers in different stages 

 of development, expressed the opinion that 

 red clover was .self -fertile. Armstrong (1) 

 maintains that there is every reason to be- 

 lieve that numerous individuals belonging 

 to Trifolltim pratense are self-fertile and 

 that they produce self -fertile progeny (ac- 

 cording to Westgate and Coe. 1, p. 3). 

 Martinet (2, p. 5) and Beat (1, p. 326j 

 also report self-fertility in red clover. Con- 

 cerning the findings of Beal, however, 

 some doubt may justly be felt as to tjheir 

 correctness. Beal states that 50 heads of 

 a plant isolated with moscpiito netting and 

 left alone produced a total of 25 seeds, 

 and that 50 heads of another likewise iso- 

 lated plant with which bumble bees were 

 imprisoned yielded a total of 94 seeds. It 

 may be argued, however, that mosquito net- 

 ting may not furnish an absolute isolation 

 as smaller insects may gain access to the 

 flowers and bring about pollination by 

 pollen from the outside of the isolation 

 cage. Furt^iermore the comparatively 

 heavy seed production on the plant on 

 w^hich bumble bees were set to work may 

 readily be explained by the bumble bees 

 bringing with them pollen, deposited on 

 their bodies, from the outside. Under the 

 circumstances. Beat's .statements appear to 

 carry little weight. 



In comparing the evidence available in 

 the matter of the fertilization of red clov- 

 er, it is ai>parent that the evidence sup- 

 porting tiie contention of self-fertility is 

 very weak and under t,he circumstances it 

 may be considered justified to conclude 

 that Red clover is normally, if not always. 

 self-sterile. 



Varieties. 



A great uundier of more or le.ss well 

 defined varieties of red clover have been 

 distinguished. For the purpose of this 

 paper they may be grouped into three 

 classes, viz. : 



Botanical varieties. 

 Biological varieties, 

 (icographical varieties. 



