Interactive key to the woody plants of Minnesota

This interactive key to the perennial woody plants of Minnesota was developed with the goal of providing an easy-to-use  guide to identification of all woody plant species occurring in the state. The key includes native species as well as naturalized introduced and commonly cultivated woody plants.

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Interactive keys have many advantages over traditional keys and ours is designed to be accessible to anyone on the web with a limited knowledge of botany. Definitions of basic plant charactertics are illustrated below. Choose a feature from the upper left window and character states will be displayed in the upper right window.  As you define characteristics of a particular specimen, only those species bearing  these characteristics will be displayed  in the lower right window.  Selecting a scientific name will produce a species description and a link to an image illustrating the species. In some browsers it may be necessary to resize the image window to view the illustration. When using measurements of length and width, enter an average value rather than an extreme value.  After eliminating all but one species, it is important to read the species description carefully to check for accuracy. Zeros values do not appear in the descriptions. For example, a description of "-1.0 cm" is not a negative value but a range of "0-1.0 cm". Data are coded in DEscription Language for Taxonomy or DeLTA format.

The information contained in the key is drawn from collections at the University of Minnesota herbarium and the following published sources: (1) Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, 2nd Edition. New York Botanical Garden. (2) Harrington, H.D. and L.W. Durrell, 1957, How to Identify Plants, Ohio University Press. (3) Rathke, D.M., 1995, Minnesota Trees, Minnesota Extension Service (4) Rathke, D.M. 1995, A Beginnerís Guide to Minnesota Trees, Minnesota Extension Service. (5) Rosendahl, C.O. and F.K. Butters, 1928, Trees and Shrubs of Minnesota, The University of Minnesota Press. (6) Tekila, S., 2001, Trees of Minnesota:  Field Guide, Adventure Publications Inc., Cambridge, Minnesota.

 

Definitions

Features are listed alphabetically, starting with qualitative characteristics and followed by quantitative traits requiring measurement. Addtionally, common names, plant families, and synonyms (old names) are included.

Growth form : Trees have a main stem (trunk). Shrubs are low in height and usually have more than one stem arising from the base. Vines are climbing plants.

Leaf apex: Tip of the leaf or leaflet. Acute: Sharply pointed.  Acuminate:  Narrowing gradually to a point. Rounded:  Semicircular outline at the apex, not pointed.

Leaf arrangement: The alternate arrangement has one leaf per node, the opposite arrangement has two leaves per node and whorled has three or more per node. Fasicles are tight bundles or clusters of leaves, as in pine needles.

Leaf base: Shape of the leaf or leaflet base where it attaches to the petiole or stem. Rounded:  Semicircular base of the leaf.  Cuneate:  Tapering or wedge shaped. Asymmetrical:  Shape of the leaf is different on one side from the other. Cordate:  Heart shaped. Truncate: The blade joining the petiole at an abrupt, right angle. Obscured: Covered by scales as in some conifers.

Leaf blade shape: Linear:  Long and narrow with parallel sides. Lanceolate:  A narrow leaf that is broadest toward the base. Ovate:  Egg shaped. Obovate:  Broadest toward the apex. Oblong:  Longer than broad with parallel sides. Elliptic:  Broadest at the middle, the ends close to equal. Deltoid:  Triangular. Cordate:  Heart shaped. Sagittate:  Arrowhead shaped.   If the leaf is lobed, trace a general outline between the lobes and the sinuses (gaps between lobes).

Leaf margin: Is the edge of the leaf smooth, saw-toothed, or deeply lobed? 

Leaf phenology: Deciduous trees lose their leaves in the fall whereas evergreen trees retain their leaves year round.

Leaf shape: The general outline of the leaf.  Scale-like leaves have overlapping flaps.  Needle-like leaves are narrow and pointed.  Blade-like leaves are planar.

Leaf type: Simple leaves have a single blade arising from the petiole or the point of attachment to the stem.  Compound leaves have multiple leaflets.  If you are confused, there should be a small bud between the stem and where the leaf attaches. Pinnately compound leaves have leaflets arranged along the length of the petiole while compound leaves have leaflets originating from a single point.

Leaf surface: Texture of the leaf surface. Glabrous: smooth. Scabrous: rough. Pubescent: hairy.

Leaf venation: Do all veins of the leaf blade run parallel to each other (parallel)? Are the veins feather-like and branching from the midrib (pinnate)? Are there more than three prominent veins at the base of the blade arranged like fingers of the hand (palmate). Are the veins net-like (reticulate) or canít you tell (indistinct)?

Origin: Native or exotic to Minnesota.

Spines: Pointed projections. Thorns are modified branches. Spines are modified leaves. Prickles are epidermal projections.

Stipules or stipule scars : Small leafy outgrowths near the base of the petiole or where the leaf joins the stem. If stipules are soon deciduous, then stipule scars may be present along the stem where the petiole joins the leaf.

Bud length: These may be very small!  Look for buds at the tip of the stem or at the point where a leaf meets the stem.   Measure a bud of average size in centimeters.

Lateral veins: Count the number of veins on one side of the main vein in pinnately veined leaves and count the number of principal veins if palmately veined.

Leaf blade length: For simple leaves, measure form the base of the blade to the apex (tip of leaf) in centimeters.  For compound leaves, make the same measurement on a leaflet of average size in centimeters. Measure the blade only (do not include the petiole in the measurement).

Leaf blade width: Measure across the blade at its widest point,.  For compound leaves, measure a leaflet of average size in centimeters.

Petiole length: The petiole connects the leaf blade to the stem.  Measure the petiole in centimeters from the base of the leaf blade (or lowest leaflet in compound leaf) to the point of attachment to the stem.  This value can be zero if there is no petiole.

Twig diameter: Measure the diameter of a stem bearing the leaves in centimeters.

Acknowledgements: We thank Michael Bartley, Erika Blackwell, Kirsten Bovee, Anita Cholewa, Wendy Clement and Summer Silvieus for assistance and the David and Lucille Packard Foundation  for financial support.

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(c) 2003 George Weiblen & Nick Deacon