Abstract: Researches on the role of involucre in the growth of cotton boll are yet scarce. This problem has not come to a conclusion although Kearney, Tep-Αванесян and some others already noticed it and pointed it out. For the purpose of acquiring further knowledge, we engaged in a number of experiments in 1954 & 1955 by removing the involucre at different growth periods of bud and observing its effect on the shedding and growing of the boll. Our field experiment proved that at different growth period of bud the influence of involucre varied at different degrees. The removing of involucre at an earlier growth period of bud caused comparatively serious shedding. The effect of involucre was not only seen in shedding but also in the decrease of fresh weight, dry weight and the weight of seed cotton. The effect of involucre on the growth of cotton boll is not invariable; it varies under different environmental factors. For example, when cotton plant comes to prime growth, the branches and leaves are cross-shading together; light intensity of the lower part between rows is weakened which decreases the photosynthesis of vegetative parts and other green parts. Here we see that involucre is incapable of producing of food to meet the growth need of bolls and other parts. Simultaneously, owing to the consumption for its own respiration and other physiological processes, the involucre increases the burden of cotton plant and heightens the shedding of cotton bolls. Furthermore, we carried on a supplementary experiment by partially shading the flower in order to compare the role of involucre with leaves and green bolls. As a conclusion, we found out that the role of involucre is being rather great; the role of the involucre of each flower almost equals to 40 CM2 area of leaf. According to the results of the above experiments we can say that involucre has comparatively significant nutritive value in the growth of cotton bolls.