Tin Trus of Texas 19 



different parts of its range. The scientific name of a plant is 

 given to it l>y the individual who first describes the species, and 

 the name of the species is usually followed by the name of the 

 man who described it. For example, Quercus alba L. means 

 that this plant was originally described by Linnaeus and given 

 the name Qnercus alba. No other plant is known by this name. 

 Scientific names should be used more extensively by all in desig- 

 nating plants, for it is only through this means that we are able 

 to know with certainty that reference is made to a definite 

 species. The name of a plant consists, usually, of two parts or 

 words, as. for example, Prosopis glandulosa, Pinus palustris, 

 Ulmus Americana, Quercus nigra. The first of these words indi- 

 cates the (j( tnis to which the plant belongs, and is always capi- 

 talized, the second indicates the species and is only rarely capi- 

 talized. 



The classification of plants is an attempt to express their 

 actual kinship, or what we are accustomed to know as blood re 

 lationship. Each kind of plant is known as a species. A species 

 consists of a group of individuals which resemble each other 

 more than they resernbleany other individual. For example, all 

 of the trees which we call Ulmus Americana are more like each 

 other than they are like any other group of trees. Then there are 

 groups of species which are more like each other than they are 

 like any other species. Such a group is known as a genus. 

 There are in our area four species, all of which are more like 

 Hums Americana than they are like any other species, but each 

 differs from it and from each other in certain essential character- 

 istics. These species are Ulmus Americana, Ulmus alata, Ulmus 

 erassi folia and Ulmus fulva. The name of the species consists 

 of the generic name which denotes the genus, and is followed by 

 the specific name which defines the species. But the genus and 

 species is not the complete expression of the relationship of any 

 given plant. There are groups of genera which resemble e^h 

 other more closely than they resemble any other genera. Such 

 groups are known as families; for example Ulmus (elms) and 

 Celt is ( hackberry) make up the family Ulmaceae. Families art- 

 like wise grouped into orders, and these in turn into larger groups. 



It should be borne in mind that, knowing the name by which 

 a plant is designated marks only the beginning of an acquaint- 



