Forest Lake High School Dichotomy Tree Key
Key to Selecting Trees by leaf or needle
1a.
1b.
Tree has flat like leaves; deciduous tree
Tree has needlelike leaves; coniferous tree
go to 2
go to 21
2a.
2b.
Tree has opposite leaves
Tree has alternate leaves
go to 3
go to 8
3a.
3b.
Tree has compound leaves
Tree has simple leaves
go to 4
go to 5
4a.
4b.
Leaves are ovate & serrated,
pinnately compound 5-9 leaflets per leaf
Leaves triangular & palmately compound 3 leaflets per leaf
Green Ash
Boxelder
5a.
5b.
Leaves have 3 lobes per leaf
Leaves have 5 lobes per leaf
go to 6
go to 7
6a.
6b.
Leaf is broadly ovate; coarse serrate, 3 lobes
Leaf is narrowly ovate; double serrate, 3 lobes
Red Maple
Amur Maple
7a.
7b.
5-7 lobes per leaf; when petiole is pulled milky substance appears Norway Maple
5 lobes per leaf; lobes are deeply cut, Silver back of leaf
Silver Maple
8a.
8b.
Tree has compound leaves
Tree has simple leaves
go to 9
go to 10
9a.
9b.
Leaflets are oblong; 16-30 1” long leaflets per leaf
Leaflets are ovate; 15-23 5” long leaflets per leaf
Honeylocust
Black Walnut
10a.
10b.
Leaves are lobed
Leaves are serrated
go to 11
go to 12
11a.
11b.
Leaves have 7-11 bristly tipped points
Leaves have 5-9 rounded lobes, apex of leaf is larger than
base part
Red Oak
Bur Oak
12a.
12b.
12c.
Leaves are double toothed
Leaves are toothed
Leaves are coarsely toothed
go to 13
go to 15
Go to 16
13a.
13b.
Base of leaf is irregular, with a prominent midrib
Leaves are oval or heart shaped
American Elm
Go to 14
14a.
14b.
Leaves have a distinctly wedge-shaped at the base, orange bark
Leaves are rounded at the base, white bark
River Birch
Paper Birch
15a.
15b.
Leaves are triangular, coarse toothed, buds have resin
Leaves are oval, fine toothed, white-gray bark
E. Cottonwood
Quaking Aspen
16a.
16b.
Leaf is elliptical; branches have thorns
Leaf is not elliptical
Hawthorne
go to 17
17a.
17b.
Leaf is ovate
Leaf is lance or linear shaped
go to 18
go to 20
18a.
18b.
Leaf is near broad as long with coarse serrate, red bud
Leaf is half as broad as long
American Linden
go to 19
19a.
19b.
Leaf is pubescent; fruit (if present) larger than 1.5”
Leaf is not pubescent; fruit (if present) smaller than 1.5”
Apple
Crabapple
20a.
20b.
Twigs are golden, leaf has a near white back
Leaves are gray, thorns and olives may be present
Weeping Willow
Russian Olive
21a.
21b.
Leaves are scale like
Leaves are needle like
White Juniper
go to 22
22a.
22b.
Needles are in fascicles (clusters)
Needles are single
go to 23
go to 25
23a.
23b.
Needles are in fascicles of 5; needles are soft
Needles are in fascicles of 2
White Pine
go to 24
24a.
24b.
Needles are twisted; bark is orange
Needles are not twisted; bark is reddish
Scotch Pine
Red Pine
25a.
25b.
Needle is flat; two white line on underside of needle
Needle is 4 sided/ almost round
Balsam Fir
go to 26
26a.
26b.
Needle is blue; prickly when handled/ cones light brown 3-5” long Blue Spruce
Needle is green/ cones dark brown 1”-1.5” long
White Spruce