Topic 2. Woody Plant Recognition

More than any other group of organisms, woody plants shape our outdoorenvironment. Woods and forests, in turn, are shaped by their physical environment.The trees we find at a site are determined by various factors such as seasonaltemperatures, rainfall, soils, and disturbances such as fire. A seed source is alsonecessary for a tree to colonize a site. By recognizing the trees in a forest, a keenobserver can discern much about the climate and the past history of that location. Inthis activity, we ask that you learn the genus names of eighteen common woodyplants that dominate sites on campus. We will begin by keying out each exampleusing the field guide from our last lab. You will then consider each example notingthe unique set of morphological characters for each genus.

Web Resources for Review at http://botit.botany.wisc.edu/botany_130/trees

1. Quercus (Oak)

White Oak Leaf

There are well over a hundred species of oak. Their fruit is an acorn. Most, butnot all, oaks have pinnately veined and lobed leaves. All oaks in Dane County aretrees with pinnately veined and lobed leaves. Two groups arerepresented in Wisconsin. The white oak group has roundedlobes. The black oak group has bristle tipped lobes. Examplesof the white oak group that you may encounter, are bur oak(Q. macrocarpa), and white oak (Q. alba); and, from the blackoak group, black oak (Q. velutina) or northern red oak (Q.borealis).

Oaks are important members of the Wisconsin woodlandand savannah communities. Their acorns are an importantsource of food for squirrels, deer and wild turkeys. Oak woodis hard and dense, and is excellent for furniture. There is adirect relationship between a wood’s density and how muchheat is released when burned, so oak, with its dense fiber-richwood, has the reputation of being the best firewood available.

Character Set for QuercusLeaf Leaf Arrangement Habit/Distinctive characters

Simple, pinnatelyveined and lobed

Alternate, but nodes areclustered at the tip of

the twig

Tree that bears acorns

2. Acer (Maples and Box Elder)

Maples all have opposite leaves and wingedfruits. Typically, like the sugar maple leaf on theCanadian flag, they

Box Elder Leaves

have simple, palmately veinedand lobed leaves. One important species oncampus, however, box elder (Acer negundo), hascompound leaves. These are either three partedlike clover, or else pinnately compound. Bothtypes of leaves can be found on the same branch.Box elder can be distinguished from ash(Fraxinus) as box elder’s leafy twigs are grassgreen. Also, box elder leaves rarely have morethan five leaflets where ash

Sugar Maple

typically has morethan five.

Sugar maple (A. saccharum), Norwaymaple (A. platanoides), silver maple (A.saccharinum) and box elder are common oncampus. Sugar maple is a native woodlandspecies with hard dense wood suited forfurniture. Its wood is often called ‘hard’ maple.It is also economically important for the sapcollected each spring used to make maplesyrup. Silver maple is typically found in wet environmentssuch as along river banks. Its wood is soft and has little or nocommercial value. Norway maple, as the name denotes, isnot a native species. It is planted all over campus as a streettree. Unlike sugar maple, these trees grow quickly, but,because their wood is soft, break down easily. Older treesfrequently must be removed for safety considerations. Boxelder is a native species that thrives in moist or wetenvironments. It is extremely prolific and difficult to kill. Ifyou cut a tree down it will simply grow new spouts andregenerate itself.

Character Set for AcerLeaf Leaf Arrangement Habit/Distinctive characters

Simple, palmately veinedand lobed(Maples), ortrifoliate and pinnatelycompound (Box Elder)

Opposite Trees that bear winged, helicopter-like fruits

3. Aesculus (Horse-chestnut and Buckeye)Members of the genus, Aesculus, have oppositely

arranged, palmately compound leaves. The genus includesnative buckeyes (Ohio and yellow), but these are notplanted on campus. On campus you will find two speciesof non-native buckeyes, horse-chestnut (A.Hippocastanum) native to the Balkans, and bottlebrushbuckeye (A. parviflora.) native to the southeastern UnitedStates. Horse chestnut grows into a handsome tree, andhas showy flowers in the spring. Bottlebrush buckeye is ashrub. A mass planting exists along the steps on the westside of Birge hall. It also has showy flowers. It spreads vegetatively to form clumps.

Character Set for AesculusLeaf Leaf Arrangement Habit/Distinctive

characters

Palmatelycompound

Opposite Tree(Horse-chestnut Ohiobuckeye) or shrub

(Bottlebrush buckeye)

4. Fraxinus (Ash)Ashes have oppositely arranged, pinnately compo

Green Ash

und leaves. Green ash (F.pennsylvanica) and the less common, white ash (F. americana) are importantmembers of Wisconsin’s woodland community. Ashwood is light and strong which makes it good formaking baseball bats, and tool handles. On campus,both green and white ash are common. Green ash isone of the most common trees in Bascom Woods.Fraxinus can be distinguished from box elder as itsleafy twigs are grey. Further, ash has a well developedconical apical bud and, generally, the leaves have morethan five leaflets. Ash fruits are winged, but are quitedifferent from the helicopter-like maple fruits of boxelder. Tragically, an introduced beetle species, theemerald ash borer, seems fated to wipe out all ournative ash species. Trees in both Michigan and Ohio arealready effected and the pest has recently been found in Wisconsin.

Character SetLeaf Leaf Arrangement Habit/Distinctive characters

Pinnatelycompound,

usually with morethan 5 leaflets

Opposite Tree/ Twigs are gray with awell developed apical bud/

Fruits are winged

5. Carya (Hickory)

Shagbark Hickory

Carya includes hickory trees and pecans. Allmembers of the genus have alternately arranged,pinnately compound leaves. Two species are native toWisconsin, shagbark hickory (C. ovata), and bitternuthickory (C. cordiformis). Both are on campus but shagbark hickory is more common. Hickories are importantwoodland species, and are an important source of foodfor wildlife. The tree, in turn, is dependent on squirrelsto disperse its seed. The wood is tough and durableand used to make handles for garden tools. Whenburned in a grill or smokehouse, the wood imparts adistinctive flavor to meat.

Character SetLeaf Leaf Arrangement Habit/Distinctive

characters

Pinnatelycompound

Alternate Tree, shagbarkhickory has a

distinctive bark andsweet nuts.

6. Lonicera (Honeysuckle)

The genus, Lonicera includes both woody vines andshrubs. The examples on campus are all shrubs. Theseare a product of hybridization between various non-native species that were originally planted asornamentals. Honeysuckle produces red berries thatare eaten by birds which spread seed

Honeysuckle

s everywhere.Honeysuckle is a pest that displaces native, moredesirable species.

Character SetLeaf Leaf Arrangement Habit/Distinctive

characters

Simple, pinnatelyveined with entire

margins

Opposite Shrub/has axillaryred fruits

7. Ulmus (Elm)

Bascom Hill has numerous largeAmerican elm trees (U. americana).These were a common sight oncampuses and in small towns until themiddle of the last century. Since then,American elm has suffered a huge die-offdue to the introduced fungal disease,Dutch Elm Disease. The trees onBascom Hill survive only because heroic Elmmeasures are made to ensure their survival.As they die, they are being replaced withother trees that require less maintenance.The enjoyment we get from these trees isbittersweet as your grandchildren won’tenjoy the experience. Elm can bedistinguished from Tilia as the leavesare more narrow and the margins are doubly toothed. The trees on Bascom Woodsproduce seed profusely and young trees are common in the woods on campus.

Character Set for UlmusLeaf Leaf Arrangement Habit/Distinctive

characters

Simple, pinnatelyveined, doublytoothed margin

Alternate Tree with asymmetricleaves and winged fruits

.

8. Tilia (Basswood and Linden)Basswood, Tilia americana, is an important

woodland species here in Wisconsin. It can be foundgrowing naturally in the woods on campus. In this class,we will study sections of basswood stems and roots tolearn about how trees grow in girth. The namebasswood is derived from bast wood. Bast are plantfibers harvested in the production of rope. As you willsee later, the bark of the tree is rich in fibers and indeedwas used for rope production. Little leaf linden, (Tiliacordiformis), a European species, is commonly plantedas a street tree on campus. Basswood has bee pollinatedflowers, and honey made from its nectar commands ahigher price.

Like Ulmus, Tilia has simple, toothed, asymmetrical leaves, that are alternatelyarranged. The leaves, however, are much broader than those of elm and the marginsare not doubly toothed.

Character Set of TiliaLeaf Leaf Arrangement Habit/Distinctive

characters

Simple, pinnatelyveined,

asymmetrical,toothed margin

Alternate Tree often withsuckers at the base/

fruits born on shootswith bracts/ buds lack

a terminal bud.

9. Betula (Birch)

Paper Birch

All birches have distinctive bark. Paper birch and river birch are plantedextensively in suburban settings. Both occur naturally in Northern Wisconsin. Paperbirch is a disturbance species. Much of the regrowth forests of the northernWisconsin forest after logging in the nineteenth century ,were almost pure stands ofpaper birch. This is a short-lived tree which cannot reproduce in the deep shade ofan old forest. I

Yellow Birch Bough with Dwarf Shoots

n contrast to paper birch, yellow birch, along with sugar maple andhemlock, dominate the Northern Mesic Forest of Northern Wisconsin. This speciescan reproduce in deep shade.

Like Ulmus, Betula has simple, toothed, asymmetrical leaves that are alternatelyarranged. The trees bear dwarf shoots, and each species has its own distinctive bark.

Character Set of BetulaLeaf Leaf Arrangement Habit/Distinctive characters

Simple, pinnatelyveined, doublytoothed margin

Alternate Trees with distinctive peelingbark/ branches with spur

shoots

10. Pinus (Pine)Pine is an evergreen conifer with needle-like leaves.

Pine is unique among the conifers in that its leaves are allborn in fascicles which are in reality little dwarf branches.There are two groups of pine, hard pines and the softpines. Hard pines have two or three leaves per fascicleand includes red, scotch and jack pines. We only haveone species of soft pine in Wisconsin and that is Whitepine (Pinus strobus).

No pine is shade tolerant, and they all depend ondisturbance to become established. However, pines canbe long-lived. White pine can live up to four hundredyears. The lumber industry in northern Wisconsin in thelate nineteenth century was dependent on old growthstands of white pine. Much of this was shipped out westto build towns such as Dodge City, Tombstone andDeadwood. Not surprisingly this industryhas collapsed as four-hundred year old trees are not really renewable from a humancultural perspective. The same fate awaits the lumbering industry in the PacificNorthwest as it depends on ancient trees which may have more value if left alone.

Character Set of PinusLeaf Leaf Arrangement Habit

Needle-like born in fascicles of twoto seven leaves

Pyramidal-shaped Trees

11. Celtis (Hackberry)Celtis occidentalis is common in thewoods on campus. Like elm, the leavesare simple, pinnately veined andalternately arranged, with toothedmargins. Unlike elm, hackberry (C.occidentalis) leaves have a long taperedtip. The bark is warty, and the twig zigzags between internodes. The leafmargins have simple teeth

Character Set - CeltisLeaf Leaf

ArrangementHabit/

Distinctive characters

Simple leaves,pinnately veined,,toothed, Tapered

tip

Alternate Tree/Warty bark/ Twigforms zig zags between

nodes.

12. Populus (Poplar)

Populus deltoides

Populus includes cottonwood (P. deltoides), and quaking aspen (P. tremuloides).The leaves are simple, pinnately veined and alternatelyarranged with toothed margins. The petioles are flattenedand this is a good distinguishing character as this can bediscerned by rolling the petiole between two fingers.Poplars have distinctive tapered buds, and a distinctivewhite bark similar to paper birch. Older trees have deeplyfurrowed bark. Poplars tend to form shoots from their rootsystems and one tree can generate a large clump. It iseconomically important as a source of wood pulp inWisconsin. After clear-cutting, a poplar woods willregenerate itself. Poplar wood is weak. Cottonwoods willgrow to immense size only to collapse under theirown weight. The genus is uncommon on campus butextremely common along stream banks and lake shores inDane county.

Character Set - PopulusLeaf Leaf Arrangement Habit/Distinctive characters

Simple triangularleaves, pinnatelyveined, toothed,

tapered tip

Alternate Tree/White bark when young furrowedwhen old/ Tends to form clumps/flattened

petioles

13. Prunus (Cherry or plum)

Prunus is a large genus that includes cherries, plums, peaches, and almonds. Threecommon species in Wisconsin are blackcherry (Prunus serotina), choke cherry(Prunus virginiana), and wild plum (Prunusamericana). The leaves are simple, pinnatelyveined and alternately arranged, with toothedmargins. Twigs when crushed may smell ofalmonds. The best field character,for native species, is that they all have smallglands on the petiole just below the blade.Black cherry is a disturbance species. It haseatable fruits that are dispersed by birds andcan spread quickly to sites when openingsare generated. It cannot reproduce inwoodland shade and depends on disturbances

for survival. Black cherry has beautiful wood th

Black Cherry

at iseconomically important for furniture. It has a distinctivescaly bark. Chokecherry grows as a large shrub or small treeand is a smaller version of black cherry. Wild plum formsshoots from its roots and one plant will spread to form alarge clump. Its fruits are eatable.

Character Set - PrunusLeaf Leaf

ArrangementHabit

Simple leaves,pinnately veined,,toothed, petioleswith two small

glands

Alternate Black cherry is a tree withdistinctive scaly bark/chokecherry is a largeshrub/ Wild plum is ashrub that forms large

clumps

White Mulberry

14. Morus (White Mulberry)

Morus alba (white mulberry) is not a native species, buthas a long history in North America. The species wasintroduced as early as 1733 in Georgia to encourage theestablishment of a silk industry in thecolony. Mulberry leaves are anindispensable food for silk worm larvae.The trees are now widespread andconstitute somewhat of a weed both onand off campus. In the summer, the femaletrees bear purple fruit that are enjoyed bybirds but not car owners. The leaves aretoothed and alternately arranged. Leafmorphology is highly variable. The sametree will bear leaves with no lobes, onelobe or three lobes. The one distinguishingfeature is that all leaves are palmatelyveined in that they have three major veinsemanating from the juncture with thepetiole. Otherwise their leaves appearpinnately veined.

Character SetLeaf Leaf Arrangement Habit

Simple, toothed, Someleaves are lobed, threeveins emanating from

petiole

Alternate Tree

15. Vitis (Grape)

Vitis riparia, the river bank grape, isextremely common on campus. Like allgrapes, it is a vine with simple leaves that arepalmately veined and lobed, and alternatelyarranged on the stem. Unlike Boston Ivy(Parthenocyssis tricuspidata), grape leaveshave finer teeth, and Boston ivy has only threelobes. The fruit is edible but contains moreseed than pulp. The commercial grape ofvintners of Europe andCalifornia is Vitis vinifera. The commercial slip-skingrapes such as Concord and Niagara are Vitis labrusca.

Character SetLeaf Leaf Arrangement Habit

Simple, palmately lobed(variable), palmately veined,

toothed margin

Alternate Vine

Virginia Creeper

16. Parthenocissus (Virginia Creeper/Boston Ivy)

Boston Ivy

See the last page for another graphic.

True ivy is in the genus Hedera which isn’t winter hardy here and cannot survivethe winter. The ivy you see climbing on the walls and through the windows of BirgeHall is Boston ivy, Pathenocissus tricuspidata. This is the same vine climbing on thewalls of Harvard and Yale and from which the name ‘Ivy League’ is derived.Boston ivy have simple palmately veined and tri-lobed leaves which are alternatelyarranged. It can be distinguished from Vitis as the leaf margins have coarser teethand the leaves are clearly three-lobed (rarely you will find palmately compoundleaves on this plant).

Virginia creeper (P. quinquefolia) is another species of Parthenocissus oncampus. It is native and grows wild in Bascomb woods. Parthenocissusquinquefolia is a vine with palmately compound leaves that are oppositely arranged.While these are in the same family as grape, and have fruits similar to grape, theirfruits are not edible.

Character Set ParthenocissusLeaf Leaf Arrangement Habit

Palmately lobedsimple leaves

(Boston Ivy), orpalmatelycompound

(Virginia Creeper)

Alternate Vine with rootsused to cling totheir substrate

17.Robinia (Black Locust)

Black Locust

Black locust (R. pseudoacacia) is a commontree along the boundaries of the woods oncampus. It is highly invasive as it will form newshoots from the roots and tends to form clumpswhen grown in the open. It has pinnatelycompound leaves that are alternately arranged.It can be distinguished from hickory by theshape and number of its leaflets. Further, unlikehickory, the axillary buds are hidden by thepetiole. The wood is dense, brittle and rotresistant. It is suited for fence posts andfirewood. In the spring it flowers profusely andin the fall it bears numerous bean-pod like fruits(legumes).

Character Set of RobiniaLeaf Leaf Arrangement Habit

PinnatelyCompound, budsare hidden by the

petiole

Alternate Tree, younggrowth frequently

has thorns

18.Rhamnus cathartica (Buckthorne)

Black Locust

Buckthorne is an escaped cultivated shrub. It has seeds that birds distribute farand wide. It can be found all over campus.

Character Set of RhamnusLeaf Leaf Arrangement Habit

Simple leaveswith a smooth

margin

Alternate/opposite.Alternate but almost

opposite.

Shrub, terminalgrowth with a

thorn

Web Lesson @ http://botit.botany.wisc.edu/botany_130/trees