Trees

LLM guided tree classification.

Simplified classification of common deciduous trees

Based on the APG system and their leaf characteristics. Class: all are Magnoliopsida (Dicotyledons) except Pine which is Pinopsida

Common Name	Genus and Species	Leaf Type	Flower Type	Order	Family	Clade
American Elm	Ulmus americana	Alternate, simple, toothed	Small, in clusters	Rosales	Ulmaceae	Eudicots (Rosids)
Black Locust	Robinia pseudoacacia	Alternate, pinnate compound, smooth edge	White, fragrant, in hanging clusters	Fabales	Fabaceae	Eudicots (Rosids)
Eastern White Pine	Pinus strobus	Spiral, needle-like	Cones	Pinales	Pinaceae	Gymnosperms
English Ash	Fraxinus excelsior	Opposite, compound, toothed	Small and inconspicuous	Lamiales	Oleaceae	Eudicots (Asterids)
English Oak	Quercus robur	Alternate, simple, lobed	Catkins	Fagales	Fagaceae	Eudicots (Rosids)
European Beech	Fagus sylvatica	Alternate, simple, smooth edge	Small flowers in spikes	Fagales	Fagaceae	Eudicots (Rosids)
European Hazel	Corylus avellana	Alternate, simple, toothed	Catkins	Fagales	Betulaceae	Eudicots (Rosids)
Honey Locust	Gleditsia triacanthos	Alternate, pinnate or bipinnate compound, smooth edge	Greenish-yellow, small, in clusters	Fabales	Fabaceae	Eudicots (Rosids)
Silver Birch	Betula pendula	Alternate, simple, toothed	Catkins	Fagales	Betulaceae	Eudicots (Rosids)
Sugar Maple	Acer saccharum	Opposite, simple, lobed	Small flowers in clusters	Sapindales	Sapindaceae	Eudicots (Rosids)
White Ash	Fraxinus americana	Opposite, compound, toothed	Small and inconspicuous	Lamiales	Oleaceae	Eudicots (Asterids)

Full Tree Taxonomy

Tree classification including all seven levels of taxonomy for each tree. Common to all:

• Kingdom: Plantae
• Broad Division¹ : Tracheophyta (vascular plants, characterized by the presence of specialized conducting tissues called xylem and phloem, which are responsible for the transport of water, nutrients, and sugars throughout the plant.)
• Specific division: Magnoliophyta / Angiosperms (seeds within fruits.)
• Class: All Magnoliopsida (Dicotyledons) except Yew which is Pinopsida

Common Name	Order	Family	Genus	Species
Aspen	Malpighiales	Salicaceae	Populus	tremula
Black Locust	Fabales	Fabaceae	Robinia	pseudoacacia
Common Alder	Fagales	Betulaceae	Alnus	glutinosa
Common Ash	Lamiales	Oleaceae	Fraxinus	excelsior
Common Lime/Linden	Malvales	Malvaceae	Tilia	x europaea
English Elm	Rosales	Ulmaceae	Ulmus	minor
English Oak	Fagales	Fagaceae	Quercus	robur
European Beech	Fagales	Fagaceae	Fagus	sylvatica
Field Maple	Sapindales	Sapindaceae	Acer	campestre
Hawthorn	Rosales	Rosaceae	Crataegus	monogyna
Honey Locust	Fabales	Fabaceae	Gleditsia	triacanthos
Hornbeam	Fagales	Betulaceae	Carpinus	betulus
Horse Chestnut	Sapindales	Sapindaceae	Aesculus	hippocastanum
Rowan	Rosales	Rosaceae	Sorbus	aucuparia
Silver Birch	Fagales	Betulaceae	Betula	pendula
White Willow	Malpighiales	Salicaceae	Salix	alba
Wild Cherry	Rosales	Rosaceae	Prunus	avium
Yew	Pinales	Taxaceae	Taxus	baccata

Naming of Trees

Levels of biological taxonomy

The naming of deciduous trees (like all organisms) is done within the framework of biological taxonomy, a hierarchical classification system that groups organisms based on shared characteristics. The key levels, from broadest to most specific, are:

1. Domain
2. Kingdom
3. Phylum/Division (Phylum is used in zoology and Division is typically used in botany)
4. Class
5. Order
6. Family
7. Genus
8. Species

Deciduous trees, being part of the plant kingdom (Kingdom: Plantae), fall under various orders, families, genera, and species, depending on their unique characteristics.

Division: deciduous trees are angiosperms

In the plant kingdom, there are several important divisions or phyla (plural of “phylum”) which represent the broad diversity of plant life on Earth. Some of these are:

1. Bryophyta: This phylum contains the mosses. These are typically small, non-vascular plants that grow in moist environments.

2. Hepatophyta: This phylum includes the liverworts. Like mosses, liverworts are non-vascular and usually small, often found in moist or wet environments.

3. Anthocerotophyta: This phylum contains the hornworts. Like mosses and liverworts, hornworts are non-vascular plants typically found in damp habitats.

4. Pteridophyta: This phylum includes ferns and related plants. These are vascular plants that reproduce via spores rather than seeds.

5. Gymnospermae (or Coniferophyta): This phylum contains the gymnosperms, which include conifers like pines, firs, and spruces. These plants are vascular and reproduce via seeds, but unlike angiosperms, their seeds are not enclosed in a fruit.

6. Angiosperms (or Anthophyta): This phylum includes the flowering plants, which are the most diverse group of plants on Earth. Like gymnosperms, they are vascular and reproduce via seeds, but their seeds are enclosed in a fruit.

Class: trees are dicots

The majority of hardwood, deciduous trees belong to the class Magnoliopsida, also known as Dicotyledons or simply Dicots. This class is one of the two major groups of flowering plants, or angiosperms, the other being Monocotyledons or Monocots (class Liliopsida).

The Dicots, including most deciduous trees, typically have characteristics such as two cotyledons (the embryonic leaves in seed-bearing plants), net-like leaf veins, and flower parts in multiples of four or five.

However, not all trees in the Magnoliopsida class are hardwoods or deciduous. The class is very diverse and also includes herbaceous plants and softwood trees. It’s also worth noting that not all hardwood trees are deciduous; some, like many species of oak and beech in warmer climates, are evergreen.

On the other hand, the majority of gymnosperms (non-flowering plants including conifers like pine and spruce trees) belong to other classes, mainly Coniferophyta (or Pinophyta). These trees are usually evergreen and are typically softwoods, not hardwoods.

Keep in mind that these are generalizations, and there are always exceptions in biology!

Tree Orders

Many trees belong to a few key orders in the plant kingdom. Each order is characterized by a unique combination of traits, which can include features of the flowers, leaves, seeds, and other parts of the plant. Here are some of the most common orders that include tree species:

1. Fabales:
   • This order includes leguminous trees like acacia, locust, and redbud, characterized by their pod-like fruit (legumes) and typically compound leaves.
   • Black Locust (Robinia pseudoacacia)
   • Honey Locust (Gleditsia triacanthos)
2. Fagales:
   • This order includes a number of deciduous trees, such as oaks, beeches, birches, and walnuts. Members of this order typically have simple leaves and flowers that are arranged in catkins.
   • Common Alder (Alnus glutinosa)
   • English Oak (Quercus robur)
   • European Beech (Fagus sylvatica)
   • Hornbeam (Carpinus betulus)
   • Horse Chestnut (Aesculus hippocastanum)
   • Silver Birch (Betula pendula)
3. Lamiales:
   • This order is mostly herbaceous but includes some trees like ashes and olives. They often have square stems and flowers with bilateral symmetry.
   • Common Ash (Fraxinus excelsior)
4. Laurales:
   • This order includes the laurel family, which contains trees like cinnamon, bay, and sassafras. They typically have aromatic leaves and flowers with many parts.
5. Magnoliales:
   • This order includes the magnolias, tulip tree, and bay laurels, among others. They are characterized by large, often fragrant flowers and aggregate fruit.
6. Malpighiales:
   • This order includes a diverse group of plants, with trees like willows, poplars, and mangroves. Characteristics are highly varied due to the diversity of the order.
   • Aspen (Populus tremula)
   • White Willow (Salix alba)
7. Malvales:
   • This order includes trees like linden and cacao. Many have simple, alternate leaves and flowers with numerous stamens often fused together.
   • Common Lime/Linden (Tilia x europaea)
8. Pinales:
   • This order is composed entirely of conifers, including pines, spruces, firs, and cedars. They are typically evergreen with needle-like or scale-like leaves and cone-bearing seeds.
   • Yew (Taxus baccata)
9. Rosales:
   • This order contains a diverse group of flowering plants, including many trees such as elms, mulberries, and rose family trees like apple, pear, and cherry.
   • English Elm (Ulmus minor)
   • Hawthorn (Crataegus monogyna)
   • Rowan (Sorbus aucuparia)
   • Wild Cherry (Prunus avium)
10. Sapindales:
    • This order includes many familiar trees like maples, horse chestnuts, and citrus trees. The flowers are usually radially symmetric, and the fruit type varies.
    • Field Maple (Acer campestre)

Angiosperm Phylogeny Group

The Angiosperm Phylogeny Group (APG) classification system works by arranging flowering plants, including trees, into clades based on the most recent genetic and molecular research. These clades are groups of organisms that are believed to have evolved from a common ancestor.

A key principle of the APG system is the use of monophyletic groups, or clades, where all descendants of a particular common ancestor are included. This is intended to reflect the true evolutionary history of plants. Monophyletic groups are in contrast to paraphyletic groups, where some descendants of the common ancestor are left out, which were sometimes used in older systems.

In terms of the actual naming of plants, the APG system doesn’t drastically change the binomial nomenclature system (genus + species) established by Carl Linnaeus. So, individual tree species would still be identified by their genus and species names, such as Quercus rubra for the red oak.

However, when it comes to higher-level classifications, the APG system often differs significantly from older systems. For example, many familiar rank-based categories such as Orders and Families may be rearranged, renamed, or have their membership altered to better represent our current understanding of plant relationships. The system also does not emphasize ranking the way older systems did, as it’s more focused on the relationship between groups.

It’s important to note that the APG system is continually being revised as new data becomes available, with the latest revision (as of my last training data in 2021) being the APG IV system published in 2016. Always refer to the most recent sources for the most up-to-date information.

Clade classification

The clade-based system of APG can indeed provide a different perspective on the relationships between these trees. However, creating such a table can be complex, as the APG system relies heavily on molecular data to determine these relationships, and the resulting clades often don’t correspond neatly to the traditional rank-based taxonomic levels. The naming of these clades often differs between sources and there is not a set list of names for each potential group of related plants.

For a simplified perspective, the APG IV system (the latest as of 2021) divides angiosperms (flowering plants) into two main clades:

1. Monocots: The monocotyledonous plants, including families like Poaceae (grasses) and Orchidaceae (orchids). They typically have one embryonic leaf (cotyledon), parallel leaf veins, and flower parts in multiples of three, among other characteristics.

2. Eudicots: The eudicotyledonous plants, which includes most of the familiar flowering plants. They typically have two cotyledons, net-like leaf veins, and flower parts in multiples of four or five.

Eudicots are further divided into several clades, including Rosids and Asterids. Most of the trees you’re interested in would fall into the Rosids clade. For instance:

• Fagales (includes beech, oak, birch, hornbeam, hazel, alder, walnut, and hickory) is a part of the Rosids clade.
• Lamiales (includes ash) is a part of the Asterids clade.

These are very high-level groupings and within each of these are numerous smaller clades, some of which might correspond to traditional orders or families, others are unique to the APG system.

Remember that this is a simplification of the APG IV system, which includes many more clades and much more detail about the relationships between different groups of plants. As of my last training data in September 2021, this is the most recent APG system. Always refer to the most recent sources for the most up-to-date information.

Footnotes

1. Phylum used in zoology.