=p.= Leaflets with 1-3 glandular notches at the base 17. _Ailanthus._

=p.= Leaflets entire at base, but very slightly serrate near the tip 16. _Cedrela._

=q.= Coat of fruit more or less dehiscent into 4 valves; nut smoothish; leaflets, except in one species, not over 11 in number, usually 5-7 82. _Carya._

=q.= Coat of fruit not regularly dehiscent; nut, in the wild species, rough-coated; leaflets, except in a cultivated species, over 11 in number 81. _Juglans._

=r.= Leaves quite regularly twice odd-pinnate; leaflets about 1 in. long; juice not milky; fruit rounded berries in large cl.u.s.ters; plant not p.r.i.c.kly; branchlets not heavy-tipped 15. _Melia._

=r.= Leaves once to twice irregularly odd-pinnate; the leaflets very irregularly and coa.r.s.ely toothed; a small, round-headed tree with bladdery pods 24. _Koelreuteria._

=r.= Leaves irregularly about twice odd-pinnate; the leaflets lanceolate; quite a low plant with few heavy-tipped branches; plant without p.r.i.c.kles 27. _Rhus._

=r.= Leaves 2 (sometimes 3) times odd-pinnate; tree-stem with p.r.i.c.kles; small tree or shrub, with few branches 44. _Aralia._

=r.= Leaves once to twice abruptly pinnate; large tree with slender-tipped branches, usually very th.o.r.n.y 34. _Gleditschia._

=s.= Leaves very large (2 ft. or more long), about twice abruptly pinnate; leaflets broad and often 2 in.

long; branches blunt; no thorns 33. _Gymnocladus._

=s.= Leaves and leaflets much smaller, leaves quite irregularly once or twice abruptly pinnate; branches slender-tipped; large tree, usually very th.o.r.n.y 34. _Gleditschia._

=s.= Leaves twice abruptly pinnate; leaflets over 400 in number, with midrib near the upper edge 35. _Albizzia._

=s.= Leaves regularly once pinnate, not over 2 ft. long.

(=t.=)

=t.= Leaves abruptly pinnate, not over 5 in. long; leaflets 8-12, small, mucronate-pointed 29. _Caragana._

=t.= Leaves odd-pinnate; shrub or small tree, with few, heavy-tipped branches; no spines or p.r.i.c.kles 27. _Rhus._

=t.= Leaves odd-pinnate; leaflets large (3-5 in. long), not usually over 11 in number; round-topped tree 30. _Cladrastis._

=t.= Leaves odd-pinnate; leaflets less than 3 in. long, frequently 11-21 in number; often with spines at the bases of the leaves in the place of stipules 12. _Xanthoxylum_ or 31. _Robinia._

=u.= Leaves palmately compound. (=CC.=)

=u.= Leaves pinnately compound. (=BB.=)

=u.= Leaves simple, evergreen, sessile, in whorls around the stem, which they completely cover (98a. _Araucaria._)

=u.= Leaves simple, opposite, evergreen, entire, over 2 in. long 61. _Osmanthus._

=u.= Leaves simple, opposite, evergreen, entire, under 1 in. long 73. _Buxus._

=u.= Leaves simple, deciduous. (=v.=)

=v.= Branches ending in thorns; small trees, or shrubs.

(=AA.=)

=v.= Plants not th.o.r.n.y. (=w.=)

=w.= Leaves palmately lobed (one variety, rarely cultivated, lacks lobes, but is heart-shaped with a serrate margin), the lobes over 3 in number, or with notches or serrations; fruit dry, winged 25. _Acer._

=w.= Lower leaves palmately 3-lobed, and heart-shaped at base, upper ones ovate, all with entire margin; fruit with juicy pulp covering the 4 seeds 66. _Clerodendron._

=w.= Leaves palmately lobed; fruit small, one-seeded, berry-like drupes in large cl.u.s.ters, with flattened stones, or large rounded cl.u.s.ters of flowers without stamens or pistils; shrubs rather than trees 47. _Viburnum._

=w.= Leaves heart-shaped, entire or slightly angulated; not lobed. (=DD.=)

=w.= Leaves irregularly serrate, somewhat straight-veined; fruit single-winged; large cultivated tree 60. _Fraxinus._

=w.= Leaves neither heart-shaped nor lobed; small trees, almost shrubs. (=x.=)

=x.= Leaves entire. (=z.=)

=x.= Leaves serrate or dentate, ovate or oval. (=y.=)

=y.= Fruit rounded drupes in large cl.u.s.ters, with single flattened stones 47. _Viburnum._

=y.= Fruit lobed pods, which burst open in the autumn; branchlets somewhat 4-sided 19. _Euonymus._

=z.= Leaves small, lanceolate; flowers and fruit large and beautiful 42. _Punica._

=z.= Leaves broad, thin, with curved parallel veins or ribs.

45. _Cornus._

=z.= Leaves large, broad, oval, without either curved or straight parallel ribs 63. _Chionanthus._

=AA.= Leaves entire and covered on both sides with silvery, peltate scales 72. _Shepherdia._

=AA.= Leaves ovate, small, minutely serrate 20. _Rhamnus._

=BB.= Leaves large, 18 in. or more long; leaflets 11 or more, very finely serrated 14. _Ph.e.l.lodendron._

=BB.= Leaves smaller; leaflets entire or quite evenly toothed, usually over 5 in number 60. _Fraxinus._

=BB.= Leaflets coa.r.s.ely and quite irregularly toothed, 3-5 (rarely 7) in number 26. _Negundo._

=CC.= Leaflets slender-lanceolate, almost entire; shrub or small tree, 5-10 ft. high 67. _Vitex._

=CC.= Leaflets broader and serrate; usually large trees.

23. _aesculus._

=DD.= Leaves with radiating ribs. (=FF.=)

=DD.= Leaves with feather-veining. (=EE.=)

=EE.= Leaves 2-6 in. long; flowers small, in large, dense, terminal cl.u.s.ters 62. _Syringa._