The Determinative Action of Environic Factors Upon Neobeckia acquatica Greene, 267 



Living plants of Neobeckia aquatica were obtained from the 

 shores of South Bay of Lake Champlain ia the autumn of 1902 and a 

 few years later a socond supply was furnished by Prof- H. C, Cowles 

 from pools in the vicinity of Chicago. Cultures from 1902 to 1906 

 were made in the soil "and in water in the New York Botanical Garden. 

 Living plants were taken to the Desert Laboratory in 1906 and grown 

 under glass as well at the Montane plantation at 8,000 feet as terres- 

 trials- Some of the individuals grown here were taken to the Coastal 

 Laboratory at Carmel, California near the shore of the Pacific in 1910. 

 Flowers were formed but once in the ten years and all reproductions 

 were from cuttings. 



Neobeckia is usually found rooted in the mud at the bottom of 

 lakes and pools at a deptli af 20 to 30 cm- Its most familiar aspect 

 is that offered by the plant in bloom when an irregularly cylindrical 

 stem extends above the surface of the water a few cm, the emersed 

 part bearing a few oblong er oblong-ovate leaves or bracts subtending 

 the terminal inflorescences. The submerged part of the stem bears 

 finely dissected leaves and a dense cluster of these are usually found 

 about the base of the stem. The plant is not found above the high 

 water leveL Almost any part of the shoot serves to propogate the 

 plant and numerous individuals may be found upon the muddy strand 

 between high and low water levels. 



Nepionic leaves of seedlings have not come under observation 

 during the course of this work. The emersion of aquatic individuals 

 is usually followed by rejuvenescence consequent upon the changes in 

 temperature, illumination, and moisture. The earlier leaves are entire 

 or nearly so and successive organs show an irregularly progressive 

 dissection of the laminae beginning at the base, which results in pinna- 

 tifid blades and finally carries the series on terrestrials into much 

 divided organs in which the ultimate parts are narrow and strap-shaped 

 {Fig. 3). These aerial dissected leaves have not the spread and extension 

 of the submerged dissected leaves, and wide differences exist between 

 the structures presented by the two types- 



The senescent leaves of aquatics are formed on the terminal por- 

 tions of stAms above the surface of the water are in ordinary appearance 

 quite like the senescent organs of terrestrials. No wild terrestrial plants 

 have been found in which stems were formed, but it seems very probable 

 that they may have been developed by many plants in a state of nature. 



A number of cultures were made to ascertain the reaction of the 

 plant under various environic conditions. Plants which had been grown 



