13a.

Leaf scars broadly triangular and conspicuous; twigs stout, pith large, pale

14

13b.

Leaf scars narrowly crescent shaped; twigs fairly slender, pith small

15

14a.

Terminal buds usually missing; pith of one-year old twigs very large and soft; shrubs

Sambucus

14b.

Terminal buds usually present and large; pith hard; trees

Aesculus

15a.

Buds with several overlapping scales

16

15b.

Buds without scales, or with 2-4 scales meeting lengthwise

18

16a.

Pair of hairy ridges run down twigs from between each pair of leaf scars; small shrubs

Diervilla

16b.

Twigs lacking hairy ridges between nodes

17

17a.

Bud scales of previous year's bud persisting around twigs; shrubs

Lonicera

17b.

Buds of previous year represented only by encircling bud scale scars on twigs; trees

Acer

18a.

Bud scales absent; pair of small leaves clearly visible

Viburnum

18b.

Buds scales present covering leaves

19

19a.

Junction of upper leaf scars forming a raised projection; buds short; trees

Acer

19b

Junction of leaf scars not raised, often notched; buds elongate, stalked; shrubs

20

20a.

Leaf scars not joined; axillary buds slender

Viburnum

20b

Leaf scars connected; axillary buds often widest above middle

Cornus

21a.

Twigs armed with thorns, spines, or prickles

22

21b.

Twigs unarmed

33

22a

Thorns (modified branches) present

23

22b

Spines or prickles

26

23a

Thorns often 2 or 3 pronged; buds nearly hidden beneath leaf scars

Gleditsia

23b.

Thorns normally unbranched; buds plainly visible

24

24a.

Buds appressed or naked (lacking scales)

Rhamnus

24b.

Buds spreading and with overlapping scales

25

25a.

Buds acute, thorns less than 3 cms long

Pyrus