Offset 



A short, basal stem by which some plants propagate. 



Oleaginous 



Refers to the production or presence of oil in a plant 

 organ, e. g., olive fruit. 



Oligocene 



The geological epoch near the middle of the Tertiary 

 period in the Cenozoic era which began about 39 million 

 years ago and lasted for about 11 million years. 



Oligosaprobic 



Refers to an aquatic habitat that is high in content 

 of oxygen, low in dissolved organic matter, and with very 

 little decomposition of organic substances that are present, 

 cf. Catarobic, Polysaprobic, Mesosaprobic. 



Oligotrophic 



Refers to ponds or lakes that are low in content of basic 

 nutritive substances for plants, lacking a distinct stratifica- 

 tion of dissolved oxygen in summer or winter, cf. Eutrophic. 



Ombrophilous 



Refers to plants that endure much rain, with leaves that 

 are easily wetted. 



Ombrophobous 



Refers to plants that do not endure much rain, with 

 unwettable leaves. 



Omnivorous 



Refers to an animal that eats both plant and animal food, 

 cf. Carnivorous, Herbivorous. 



Ontocline 



A gradation in phenotypic characteristics such as color or 

 form appearing at different times in the life cycle of an ani- 

 mal, may be related to the Ecocline (q. v.). 



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