Plant Identification: Examining Leaves

To identify an item is to recognize the item and associate it with its appropriate name. Such as, that tan automobile in front of our house is a Honda Accord. Or, that large woody plant in the park is a tree, more specifically a Doug-fir. Identifying a landscape or garden plant requires recognizing the plant by one or more characteristics, such as size, form, leaf shape, flower color, odor, etc., and linking that recognition with a name, either a common or so-called scientific name. Accurate identification of a cultivated plant can be very helpful in knowing how it grows (e.g., size shape, texture, etc.) as well as how to care and protect it from pests and diseases.

First let’s look at some common characteristics of plants that are useful in identifying them. Now if this was a botany class dealing with plant systematics, the field of study concerned with identification, naming, classification, and evolution of plants, we would spend a good deal of time on the reproductive parts of plants, i.e., mostly the various parts of the flowers, i.e., ovary, stigma, etc. Structural similarity of reproductive parts is an important means by which plants are categorized and grouped, and hence identified. However, with many horticultural plants, especially woody plants, we may have to make an identity without regard to flowers, for often flowers are not present or are very small and other characteristics may be more obvious. Some plants characteristics are so obvious or unique that we can recognize them without a detailed examination of the plant. Similarly, we can probably all recognize a Volkswagen Beetle without having to read the nameplate on the car.

Leaves are often the basis for identifying plants since they are so easily observed. They usually consist of two parts,

First be aware that all the leaves on a given plant do not have the same size or even appearance [Betula papyrifera, shoot, comparison]. They may vary in size, color, and even shape [Sassafras albidum, leaves, fall] and [Malus sargentii, leaves, fall]; those that receive much sun may look different from those in heavy shade. So when trying to determine the identity of a plant by its leaves, make sure you examine many leaves and attempt to determine what might be considered “typical” leaf characteristics. Although basketball players may vary in size, shape, and color, a “typical” physical characteristic of a basketball player often is “tallness”.

The pattern by which leaves are attached to a stem or twig is also a useful characteristic in plant identification. There are two large groups, alternate and opposite patterns, and a third less common pattern, whorled.

Leaves may be lobed or not lobed. A lobe may be defined as a curved or rounded projection. With leaves there is no clear distinction between shallow lobes and deep teeth. A main vein is often visible in a lobe, this may not occur in teeth.

Another important leaf characteristic for plant identification is the edge or margin of a leaf or leaflet. Leaves have either smooth edges, called entire, or small notches or “teeth” along the margin.

References:
Cope, E.A. Muenscher’s Key to Woody Plants: An Expanded Guide to Native and Cultivated Species. 2001. Cornell University Press, Ithaca, New York.

Partyka, R.E., J.W. Rimelspach, B.G. Joyner, and S.A. Carver. 1980. Woody Ornamentals: Plants and Problems. ChemLawn Corp. Columbus, Ohio.

First letter of genus (or a *Genus* itself)
Volume 1	A Abelia Abeliophyllum Abies Acer Actinidia Adenium Adenocarpus Aesculus Ailanthus Akebia Albizia Alnus Amelanchier Amorpha Ampelopsis Andromeda Aralia Araucaria Arbutus Arctostaphylos Ardisis Aronia Artemisia Asimina Atriplex Aucuba Azara B Baccharis Bauhinia Berberis Betula Brachyglottis Buddleia Bumelia Buxus C Callicarpa Calluna Calocedrus Calycanthus Camellia Campsis Caragana Carnegiea Carpinus Carya Caryopteris Castanea Catalpa Cathaya Ceanothus Cedrus Celastrus Celtis Cephalanthus Ceratonia Cercidiphyllum Cercidium Cercis Cercocarpus Chaenomeles Chamaecyparis Chilopsis Chimonanthus Chionanthus ×Chitalpa Choisya Chrysolepis Chrysothamnus Cinnamomum Cistus Cladrastis Clematis Clerodendrum Clethra Coleogyne Cornus Corylopsis Corylus Cotinus Cotoneaster Crataegus Cryptomeria Cunninghamia ×Cupressocyparisa Cupressus Cydonia Cytisus D Daboecia Daphne Daphniphyllum Dasiphora Davidia Deutzia Diospyros Dirca Disanthus Drimys E Edgeworthia Elaeagnus Encelia Enkianthus Ephedra Erica Eriobotrya Escallonia Eucalyptus Eucommia Euonymus Exochorda
Volume 2	F Fagus ×Fatshedera Fatsia Feijoa Ficus Firmiana Forsythia Fouquieria Fothergilla Fragaria Franklinia Fraxinus Fremontodendron Fuchsia G Garrya Gaultheria Genista Ginkgo Gleditsia Grevillea Gymnocladus H Hakea Halesia Hamamelis Hebe Hedera Heptacodium Hibiscus Hippophae Holodiscus Hovenia Hydrangea Hypericum I Iberis Idesia Ilex Illicium Itea J Jasminum Juglans Juniperus K Kalmia Kerria Kniphofia Koelreuteria Kolkwitzia L Laburnum Lagerstroemia Larix Larrea Laurus Lavatera Leucothoe Leycesteria Ligustrum Lindera Liquidambar Liriodendron Lithocarpus Lithodora Lonicera Loropetalum Luma M Maackia Maclura Magnolia Mahonia Malus Manglietia Menziesia Metasequoia Microbiota Morus Myrica Myrica Myrtus N Nandina Neviusia Nothofagus Nyssa O Oemleria Olea Olearia Oplopanaxa Osmanthus Ostrya Oxalis Oxydendrum
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