334 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 13 



Suffrutescent — Perennial plants in which the upper parts of the branches die 



back during an unfavorable season, but at least the lower part of the stem 



or stems is more or less woody and perennial. 

 Therophyte — An annual plant, dying at the close of a single growing season. 

 Thermograph — An instrument for producing a continuous record of temperature 



during a certain time in a given locality. 

 Tolerant — A term referring to the ability of a plant to withstand unfavorable 



elements of its environment; as shade tolerant, lime tolerant, etc. 

 Troposphere — That part of the earth's atmosphere in which there is a regular 



decrease of temperature with increasing altitude; below about 11 kilometers 



(37,000 feet). 

 Tufa — A rock composed of indurated volcanic ash. 

 Widespread — A term applying to plants which occur in many parts of a given 



area, but not abundant in any part. 

 Woodland — Vegetation composed predominately of tree life-forms, growing in 



an open condition without a closed or interlacing canopy. 



