76 Kansas Academy of Science. 



then promptly sheds its limp aments with their depleted anthers. Between the ex- 

 tremes mentioned, or say between April 10th and April 2oth, every cottonwood tree, 

 male and female, in and around Topeka, has fulfilled its estival mission and started 

 in untold numbers the germs of future cottonwood trees. 



II. 



Not wishing to dwell on the annual periodicity of development in plants, features 

 that are so well known, I turn now to the second division of this subject, and speak 

 of certain daily motions in plants, showing that they are cognizant of light and 

 darkness, as of heat and cold. In addition to that, I will attempt to show that 

 plants are sensitive to varying conditions of the atmosphere, to touch, and even to 

 contiguity of objects. 



Plants can feel, of course; but do they actually see? 



How often have we seen potato-sprouts, turnip-tops, and other plants in the 

 cellar, stretching out as far as possible and leaning over in an attempt to reach the 

 window where the only feeble rays of light enter the cellar. In the same way you 

 have all seen, in the open air, the leaves turn their faces up to the light, and when 

 they grow on the side of a house, turn sidewise to the light; and if under a roof, 

 will still turn their faces toward the brightest light. And the tendrils, those modified 

 forms of leaves, always turn away from the light. 



We are not aware that we are cognizant of light by any organ except our eyes, 

 and we call that seeing. The plant is cognizant of light in its leaves, in all their 

 modifications. Is it not, at least, analogous to seeing? Is it heresy to say that, so 

 far as light is concerned, plants can see? 



Everybody knows that the morning glory opens in the early morning, and that 

 the evening primrose opens about sunset ; but not everyone knows that each different 

 species of flower opens regularly each day at its own appointed hour. For instance, 

 our common morning glory (Ipomuea purpurea) opens before 5 o'clock, and the 

 blue morning glory ( Ipomoja hederacea) opens after 5, or about an hour later. 

 Similarly, our wild bush morning glory of the prairies (Ipomcea leptophylla), the 

 immense roots of which many of our western Kansas farmers have encountered 

 with the plow, opens at 4 o'clock in the morning, very regularly; and two other 

 species of morning glory, both with small white flowers, open still earlier. One of 

 these (Convolvulus arvensis) has small, arrow-shaped leaves, and creeps on the 

 ground; theother (Ipomoea lacunosa) has medium-sized, heart-shaped leaves, witha 

 small lobe on each side, and climbs. Both of these have tuberous roots, and hence 

 are, in a sense, perennial. The common white morning glory of our hedges and 

 thickets (Convolvulus sepium ) opens very early in the morning, perhaps soon after 

 midnight; and yet another, the common white creeper (Convolvulus spithamreus), 

 opens several hours before midnight, or late in the evening; hence is called the 

 evening beauty. Several other species of Ipomoea, commonly called moon-flowers, 

 open at early evening and close at daylight. 



One remarkable thing about this family of morning glories remains to be told: 

 all the night-blooming species are pure white, and all the morning-blooming kinds 

 are colored. True, there are white varieties of many of the day-blooming kinds, as 

 a white variety of the purple morning glory, a white variety of the blue morning 

 glory, a white variety of the red flowered cypress vine, etc.; but in all of these there 

 are traces in the center, or along the ribs of the corolla, of the original color, and 

 none of them is pure white. 



The evening primroses, too, have just as great variation in their times of bloom- 

 ing. Thus, the common great-flowered evening primrose ((Enothera grandiflora) 

 opens very promptly at 7 o'clock in the evening, and wilts about 7 o'clock next 



