=R.= Leaf-buds long and slender; fruit a small prickly bur with two triangular, horny-coated nuts; large trees 90. _Fagus._ =R.= Fruit an elongated catkin with large leaf-like bracts; bark close, gray, on a grooved trunk 87. _Carpinus._ =R.= Fruit a hop-like catkin; bark brownish, finely furrowed 86. _Ostrya._ =S.= Plant more or less thorny; shrub or small tree; fruit rounded berries ending in persistent calyx-lobes 38. _Cratægus._ =S.= Plant not thorny. (=T.=) =T.= Leaf deeply pinnatifid, usually with the basal lobes completely separated; cultivated 37. _Pyrus._ =T.= End of leaf as though cut off; sides with one large lobe; margin entire; large tree 2. _Liriodendron._ =T.= Lower leaves three-lobed, heart-shaped at base, upper merely ovate, margin entire; small tree or shrub 66. _Clerodendron._ =T.= Not as above; leaves usually many-lobed. (=U.=) =U.= Leaves thin; bark of trunk peeling off in thin horizontal strips 83. _Betula._ =U.= Leaves thin; leaf-buds long, slender, sharp-pointed; bark smooth, not peeling; cultivated 90. _Fagus._ =U.= Leaves thickish; bark roughish; fruit an oval woody cone, remaining on through the year 84. _Alnus._ =U.= Leaves thick; fruit an acorn 88. _Quercus._ =V.= Leaves evergreen, small, 2-3 in. long, thick, with revolute margins; fruit an acorn 88. _Quercus._ =V.= Leaves evergreen, oval to lance-oval, usually large; small trees, almost shrubs. (=d.=) page 56. =V.= Leaves deciduous (some are evergreen in the Southern States). (=W.=) =W.= Plant more or less spiny. (=c.=) =W.= Plant not at all spiny. (=X.=) =X.= Leaf-blade thin, long, pointed, with curved parallel veins or ribs 45. _Cornus._ =X.= Leaf-blade thin, circular or broadly oval in outline, with blunt, almost rounded apex; veins not regularly parallel 27. _Rhus._ =X.= Leaf quite elongated, 5 or more times as long as wide. (=b.=) =X.= Leaves with none of the above peculiarities. (=Y.=) =Y.= Deciduous bud-scales (stipules), leaving a scar or mark completely around the stem at the base of the leaves. 1. _Magnolia._ =Y.= Leaves covered on one or both sides with silvery scales 71. _Elæagnus._ =Y.= No such ring around the stem, or silvery scales on the leaves. (=Z.=)