tribution of roots along the side of a trench in the soil and 

 the above-ground parts of the plants along the line. 



Bisexual 



The presence of functional male and female organs in 

 the same plant or animal, cf. Hermaphrodite, Dioecious, 

 Monoecious. 



Bivalent 



A pair of Homologous chromosomes in a certain stage of 

 cell division. 



Bivoltine 



Refers to organisms with two generations a year. cf. Uni- 

 voltine, Multivoltine. 



Black Alkali 



Highly alkaline soil covered with a dark incrustation of 

 carbonates of sodium or potassium, cf . A Ikali soil, Saline soil. 



Black Earth 



See Chernozem. 



Blizzard 



A storm in which the cold wind, usually of high velocity, 

 drives fine snow and often ice crystals; the visibility is greatly 

 reduced. 



Bloom 



(1) A fine pale gray granular layer, often waxy, occurring 

 commonly on the surface of plant organs such as leaves and 

 fruits, e. g., the grape fruit. (2) A sudden appearance of brief 

 duration of large numbers of minute organisms, usually 

 algae, in bodies of water. 



Blowout 



An excavation in loose soil, usually sand, produced by 

 wind. 



56 



