Tin Trees of Texas 



21 



these terms, when his decision will be in favor of "II." Then he 

 must determine whether the leaves are opposite or alternate on 

 the stem. Here his decision goes to "B," leaves alternate. Under 

 ' B," the choice goes to "2," leaves with "netted veins." then to 

 "b," "leaves with only one primary vein at base." The next 

 choice is between "leaves entire and blade of leaf serrate or 

 notched," " (1) " or " (2)." In this case the second is found 

 correct. After this the choice falls on " (a)," "veins of leaves 

 straight, ' ' not prominently branched then k k y . " Trees not thorny 



II. Leaf Edges. 



1. Senate (saw-toothed). 2. Dentate (toothed). 3. Crenate (scalloped). 

 4. Undulate (wavy). 5. Sinuate (bayed). 6. Incised (jagged). 



and finally " (x) " leaves oblique at base, and "m" fruit a 

 circular samara, leaves harsh to the touch. This leads unerr- 

 ingly to the genus Ulmus, and no other tree in our flora can be 

 placed here if the observations are carefully- made and each deci- 

 sion accurately drawn. Turning to the page reference a descrip- 



III. Leaf Tips. 



3. Acuminate. 2. Acute. 3. Obtuse. 4. Truncate. 5. Retuse. 6. Emar- 

 ginate. 7. Obcordate. 8. Cuspidate. 9. Mucronate. 



tion of the genus is given. Here again the student should check 

 each statement in the description, to see if it tallies with the speci- 

 men at hand. If correct, the key to the genus must next be con- 

 sulted. Here the choice goes to "flowers opening in the spring 

 before the leaves." "Branches not corky winged." "Leaves 

 smooth or somewhat roughened above, inner bark not mucilagin- 



