Baker County Arboretum Dichotomous Key
A dichotomous key is a tool that allows the user to determine the identity of items
in the natural world, such as trees. Keys consist of a series of choices that lead the
user to the correct name of a given item.
To use the key, start by determining which number category the tree fits into (listed
1, 2, 3, 4, or 5). Then (within the numbered category) determine which
subcategory (listed i, ii, iii, iv, etc.) the tree fits into, and so on. By eliminating
certain characteristics, the user should be led to the correct name of the tree in
question.
Baker County Arboretum Dichotomous Key:
1. Trees with acerose (needle-like) or awl-shaped (scale-like) leaves
i. Needles held in bundles
a. 2 needles per bundle………Spruce Pine (Pinus glabra)
b. 3 needles per bundle………Longleaf Pine (Pinus palustris)
ii. Scales: tiny, overlapping.........Southern Red Cedar
(Juniperus virginiana var. silicicola)
2. Palms
i. Costapalmate leaves..........Cabbage Palm (Sabal palmetto)
3. Trees with opposite leaves
i. Simple leaves with lobes
a. Leaf petioles (leaf stalks) are red……… Red Maple (Acer rubrum)
b. Leaf petioles are not red…………..Florida Maple (Acer barbatum)
ii. Simple leaves without lobes
a. Serrate leaf margins……..Rusty Blackhaw (Viburnum rufidulum)
b. Entire leaf margins……… Fringetree (Chionanthus virginicus)
iii. Odd-Pinnately compound leaves
a. Entire or partly serrate leaf margins
i. Leaflets 4-6 inches long, 1 ½ inches wide; dark green &
smooth above with undersides paler and very pubescent
(hairy) .……..……Green Ash (Fraxinus pennsylvanica)
ii. Leaflets 3-5 inches long, 1 ½ - 3 inches wide; dark green &
smooth above; undersides paler and more or less pubescent
(hairy)……..……..White Ash (Fraxinus americana)
4. Trees with alternate leaves
i. Simple, Cordate (heart-shaped) leaves, sometimes flattened at the base
a. Entire leaf margins……….Oklahoma Redbud
(Cercis reniformis ‘Oklahoma’)
b. Serrate leaf margins………Basswood (Tilia americana)
ii. Simple leaves with lobes
a. Variable leaf lobing on one tree……..Red Mulberry (Morus rubra)
b. Sharp-pointed lobes
i. Leaves dark green above, rusty and pubescent (hairy) below;
leaves extremely variable with 2 basic types on the same or
different trees: (1) with 3 bristle-tipped lobes or (2) deeply 5to 7-lobed………Southern Red Oak (Quercus falcata)
ii. Leaves with 7-9 bristle-tipped lobes each with secondary
lobes………Shumard Oak (Quercus shumardii)
iii. Leaves with 5-7 lobes, having finely serrate
margins………Sweetgum (Liquidambar styraciflua)
iv. Leaves are 4-lobed with a wide leaf base………………...
…………………...Tulip Poplar (Liriodendron tulipifera)
c. Rounded lobes……… White Oak (Quercus alba)
iii. Simple leaves with smooth entire leaf margins, no lobes
a. Lower leaf surface or veins rusty brown……. ‘Little Gem’ Magnolia
(Magnolia grandifloria ‘Little Gem’)
b. Lower leaf surface silver gray………‘High Rise’ Live Oak
(Quercus virginiana)
iv. Simple leaves without entire leaf margins, having teeth
a. Serrate (single serrate) margins and prominent, straight, parallel
secondary veins
i. Leaves dark green above, yellow-green below; smooth and
shiny………American Beech (Fagus grandiflora)
ii. Leaves green above, lighter green and tomentose (matted hair)
below.........Swamp Chestnut Oak (Quercus michauxii)
iii. Leaves shiny dark green, leathery; exfoliating showy bark….
……………………….Chinese Elm (Ulmus parvifolia ‘Drake’)
b. Serrulate (doubly serrate) margins and parallel secondary veins
i. Smooth gray/blue bark......... American Hornbeam
(Carpinus caroliniana)
ii. Scaly brown/black bark……… Eastern Hophornbeam
(Ostrya virginiana)
iii. Scaly reddish/brown bark……...Flatwoods Plum
(Prunus umbellata)
iv. Stems have wing-like outgrowths and leaves are 1 ½ to 3 ½
inches long......... Winged Elm (Ulmus alata)
v. Stems do not have wing-like outgrowths and leaves are 4 to 6
inches long……… American Elm (Ulmus americana)
vi. Leaves pubescent (hairy) when young becoming smooth above
but retaining pubescence along veins beneath……...
…………………………….River Birch (Betula nigra)
c. Crenate leaf margins.........Weeping Yaupon Holly
(Ilex vomitoria ‘Pendula’)
d. Spines on margins……… American Holly (Ilex opaca)
v. Compound leaves
a. Odd-pinnately compound leaves with entire margins
i. Undersides of leaves pubescent (hairy)…….Mockernut Hickory
(Carya tomentosa)
ii. Undersides of leaves are smooth………..Pignut Hickory
(Carya glabra)
b. Odd- or even-pinnately compound leaves………Black Walnut
(Juglans nigra)
5. Trees with sub-opposite leaves (leaves may be alternate on vigorously growing
branches
i. Leaves with entire margins and pubescent (hairy) undersides (especially
when young)………Crape Myrtle (Lagerstroemia indica)