Haploid 



Refers to an organism or part of one in which the nuclei 

 contain a single set of Chromosomes, i.e., one Genome (q. v.), 

 e.g., Spores, Gametes, Gametophytes, certain male animals 

 such as bees. cf. Diploid, Tetraploid, Polyploid. 



Hardening 



The increase in resistance to frost in a plant tissue. 



Hardiness 



The capability of plant tissue to survive the formation of 

 ice crystals within them. cf. Frost resistance. 



Hardpan 



A cemented, hardened layer in the soil, cemented by iron 

 oxide, silica, organic matter, or some other substance, cf. 

 Claypan. 



Hard Seed 



The condition of some seeds in which water absorption 

 and germination do not occur although the environmental 

 conditions are favorable, e.g., seeds of many legumes and 

 trees. 



Hardwood 



The wood of a tree in the Angiosperms (q. v.), e.g., the 

 oak, in contrast to Softwood (q. v.). 



Haustorium 



A specialized organ of certain parasitic plants which 

 penetrates the Host and absorbs food from its tissues, e.g., 

 special hyphal branch, a specialized structure in dodder. 



Hay 



The dried, mowed stems and leaves, often including also 

 flowers or fruits and seeds, of grasses and forage legumes 

 such as alfalfa and clovers, cf. Fodder, Stover. 



Headquarters 



The main center or centers of activity of an animal, e.g., 



167 



