156 BUDS AND LEAVES 



able distance, as in mullein; it is amplexicaul or clasping if 

 the blade more or less completely surrounds the stem at the 

 point of attachment, as in New England aster; it is perfoliate 

 when the base of the blade grows together around the stem, 

 as in bellwort; it is connate-perfoliate when opposite leaves 

 cohere and surround the stem, as in boneset; it is an open 

 sheath when the part below the blade surrounds the stem, 

 often as far as the next node, but the margins are not 

 grown together; it is a closed sheath when its margins 

 are grown together around the stem. 



Forms of the Base. The base is acuminate when the blade 

 tapers sharply into the petiole, as in spicebush; it is cuneate 

 when it gradually tapers into the petiole and appears wedge- 

 shaped, as in white oak; it is acute when it forms a sharp 

 angle, as in dogwood; it is obtuse when it is blunt or rounded, 

 as in wild cherry; it is tr/uncate when it ends abruptly, the 

 edge being nearly at right angles to the petiole, as in the 

 aspen ; it is oblique when it extends for a greater distance along 

 one side of the petiole than the other, as in the elm; it is 

 cordate when two rounded basal lobes extend below the point 

 of attachment of the petiole, as in wild aster; it is reniform 

 when the basal lobes are larger and broader than in the cor- 

 date form, the leaf being broader than long, as in wild ginger; 

 it is auriculate when the lobes are small and rounded, as in 

 aster; it is hastate when the two sharp pointed, basal lobes 

 of the leaf point outward, as in pigweed and sorrel; and 

 finally the base is sagittate when the basal lobes of the leaf 

 point downward, as in tear-thumb and arrowhead. 



Forms of the Margin. The margin is entire if it is not 

 divided or indented in any way, as in sassafras; it is repand 

 when the margin is wavy, as in witch-hazel; it is sinuate 

 when the undulate indentations are deep, as in chestnut oak; 

 it is crenate when the margin has numerous rounded divisions 



