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Classy Trees
Article #377, December 2025
By Bill Cook

All forestry schools teach tree classification as a basic course.  Lots of Latin names.  Groups of similar trees, in at least some ways.  It’s kinda fun but not for everybody. 

    When Carolus Linnaeus (nee Carl von Linné) began naming living things with Latin terms, there needed to be a method of classification.  Without the benefits of genome identification and advanced ecological knowledge, Carl and others resorted to how organisms appeared.  For plants, including trees, flower structure was the most common parameter, but other parts were used, too. 
    Yep, all trees have flowers.  Some are even showy, such as gray dogwoods and magnolias.  Leaves, twigs, branching patterns, and several other characteristics can be used to plunk a species into a category.  Some bedfellows are obvious, such as maples.  Although, the maple family also includes boxelder, sometimes called ash-leaved maple.  And not too far away in relationships are buckeyes and the invasive Tree of Heaven. 
    “Opposite branching” in Michigan trees can be found only among the “MAD Horse” species; maples, ashes, dogwoods, and horse-chestnut.  Everybody else has “alternate branching” patterns.  A fallen leaf leaves a scar on the twig.  Trees within some genera have very similar leaf scars, especially useful in separating species of ash.  Such similarities can also be found among the details of buds and leaves. 
    Taxonomic purists would correctly argue that evergreens don’t “technically” have flowers.  They are called “Gymnosperms”, or those plants with naked seeds.  Pines and their needled allies have structures that end up with unprotected seeds within cones.  Broad-leaved trees are called “Angiosperms”, meaning seeds within protective (fruit) tissues.  A note about the word “fruit”.  It’s not just a sweet food.  Botanically, it’s the plant structure that holds the seeds.  So, yes Virginia, tomatoes are fruits.  So are nuts. 
    Knowing the Latin names is handy when traveling around North America or abroad.  Scientists like the Latin names because there is only one per species, unlike common names, which a species can have several, even with the same language.  Is red pine the same as a Norway pine?  And, what is a “spruce pine”?  Or more confusing, how about hornbeam, hophornbeam, American hornbeam, musclewood, and ironwood?  Uffda.
    An introductory biology course always has a section in the syllabus about the Linnaean system of classification.  The traditional headings used are kingdom, phylum, class, order, family, genus, and species.  Then, there are newer taxa, such as ”domain”, “clades”, “division”, “sub” this or that, et alia.  For the most part, the genus and species are the most utilitarian units for most of us, kinda like a first name and last name. 
    Genus and species have some marvelous language that can roll off one’s tongue like liquid butter.  Liriodendron tulipifera.  Liquidamber styraciflua.  Aesculus hippocastanum.  Elaeagnus angustifolia.  Robinia pseudoacacia.  Ah, poetry in Latin.  The genus name is always capitalized.  The species name is never capitalized, even if it’s something like “americana” or “canadensis”. 
    One curious little factoid is the name of the brown rat (Rattus norvegicus).  Linnaeus was Swedish, and proud of his heritage.  Therefore, he named one of the most reviled animal species after the Norwegians, historic antagonists.  Who said scientists don’t have a sense of humor?
    As to forest trees, as opposed to residential trees, Michigan has about 14 orders, 25 families, 46 genera, and close to 100 species.  That’s actually a reasonably high level of diversity across 20 million acres, compared to forests around the world. 
    Nosing around at the genus level, the largest genus by far, using wood volume as a measure, is “Acer”.   The maples.  Michigan sports eight species, with only one alien.  Acer spp. (spp. means multiple species within a genus) is followed by “Pinus” (pines) and then “Populus” (aspens).  Oaks and allies have a notable mention (mostly Quercus spp.), as does northern white-cedar (Thuja occidentalis). 
    Learning a tad of Latin can help better understand some species, especially in terms of geography.  In addition to the obvious “americana” and “canadensis”, or “occidentalis” and “orientalis”, consider “alleghaniensis”, “caroliniana”, “virginiana”, or “florida”.  Color is often latinized with species names such as “rubra”, “nigra”, or “alba”.  Can you imagine other associations with words such as “balsamea”, “pungens”, “papyrifera”, “ellipsoidales”, or “deltoides”? 
    Learning about tree species identification is called “dendrology”.  The science of knowing the ecological requirements and biological adaptations of a tree species is called “silvics”.  Applying both dendrology and silvics to forest management is called “silviculture”.  And, yeah, that ‘s more Latin for you. 

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TRAILER- This website was created by a consortium of forestry groups to help streamline information about forestry and coordinate forestry activities designed to benefit the family forest owner and various publics that make up our Michigan citizenry.  This website is maintained by Bill Cook, Retired Michigan State Extension Forester/Biologist.  Direct comments to cookwi@msu.edu or 906-786-1575.