NO. 3 DUNKLE : PLANT ECOLOGY, CHANNEL ISLANDS 333 



Formation — Vegetation occupying a natural area characterized by rather uniform 



climatic or edaphic conditions, having a more or less physiognomy, but with 



communities of different floristic composition, these last being sometimes 



termed the plant associations of the formation. 

 Geophyte — A perennial plant whose propagating organs for the growing season 



lie below the surface of the earth, as in bulbs, corms, tubers, and many 



rhizomes. 

 Halophyte — A plant which grows on saline or alkaline soil. 

 Hetnicryptophyte — A perennial plant with its propagating organs at the surface 



of the soil, as in the case of many rhizomes, herbs with a tap root, and 



certain low suffrutescents. 

 Hydrotherm — A combination of two graphs showing precipitation and temperature 



at stated intervals in a given locality. 

 Hygrograph — An instrument producing a continuous record of relative humidity 



for a certain period. 

 Hydrophyte — A plant which lives in the water or in wet or saturated soils. 

 Hygro-thermogram — A combination of two graphs showing both temperature and 



relative humidity for a specified time in a given locality. 

 Indigenous — Native to a given area; not introduced. 

 Initial endemic — A plant species of recent origin and not spread beyond a very 



limited area, because of lack of time or difficulty in migration, or both. 

 Isohyet — A line indicating areas of equal precipitation. 

 Local — A frequency term indicating that a given plant species may be found 



in one or only a very few parts of a given area. 

 Limiting factor — A condition that limits the development of a plant species or 



of a plant community. 

 Master factor — One, of the paramount environmental conditions exerting more 



or less of a controlling influence over a type of vegetation. 

 Megaphanerophyte — A tree over 30 meters (100 feet) high; most forest trees. 

 Mesophanerophyte — A tree or large shrub 8 to 30 meters (25 to 100 feet) high; 



most trees or large shrubs of woodlands or savannas. 

 Microphanerophyte — A shrub or small tree 2 to 8 meters (6^ to 25 feet) high; 



most shrubs of the chaparral. 

 Nanophanerophyte — A woody plant ^ to 2 meters (10 inches to 6^ feet) high; 



most shrubs of the coastal sage brush, fire-type chaparral, and desert shrub. 

 Nearctic region — An obsolescent term referring to North America as far south as 



Mexico. 

 Normal spectrum — A list of percentages of the life-forms of Raunkiaer which is 



supposed to represent their proportions under the average conditions for the 



entire world. This is used as a norm with which to compare the biological 



spectrum of any region, the important feature being the amount of deviation 



of that region from the normal. 

 Orogeny — The process of mountain building, characterized by tangential stresses 



operating for periods of relatively short duration geologically. 

 Occasional — A frequency term used to indicate that a given plant species is 



relatively uncommon and that it might not be found without considerable 



search. 

 Rain shadoiv — An area to leeward of an elevation, with less precipitation than 



occurs on the windward side. 

 Relict endemic — A plant species of more general distribution in the geologic 



mass, whose range has been restricted by changing environmental conditions, 



to one locality, or a few nearby communities. 

 Riparian vegetation — Vegetation growing along streams or rivers. 

 Savanna — Grassland with trees or shrubs growing well separated or in small 



groups. 

 Sclerophyll — A term referring to the foliage of vegetation found in climatic re- 

 gions with arid summers; leaves evergreen, reduced in size, and more or 



less thickened and coriaceous. 

 Scrub — Any community in which shrubs, suffrutescents, or dwarf trees dominate. 

 Sere — A plant succession. 

 Society — A plant assemblage within an association, consisting of subordinate 



species which have assumed temporary dominance. 



