There are many thousands of tree species in the world, which of course are part of an even larger plant kingdom. Before the scientific naming came into existence, the use and misuse of common names caused a lot of confusion.
The system of scientific names was first introduced by Carolus Linnaeus in 1753. This system now called “binomial nomenclature” used for naming living things, including plants. Moreover, the system names a species with Latin names made up of two parts, its genus and species.
The genus, the lowest level of grouping, always comes first in the scientific name.
Expanding on this botanists have grouped plants in taxonomies, a grouping based on plants with similar characteristics. These groupings are sub divided until you get down to the plant itself, the species which gives the tree its scientific name.
What is the Taxonomy Structure for trees?
The table below is an example of the structure for the genus for oak.
Genus is the lowest level of grouping. The plural of genus is genera.
A species scientific name will have two parts, first its genus and second a Latin name that is unique to the species.
Furthermore, looking at the plant kingdom regarding trees, there are 5 Divisions containing trees.
These are with their scientific names in brackets;
- Flowering plants (Magnoliophyta).
- Conifer (Pinophyta).
- Ginkgos (Ginkgophyta).
- Cycads (Cycadophyta).
- Ferns (Pteridophyta).
Additionally, there is an additional type of grouping that is sometimes used, sitting alongside this taxonomy, that is named clade.
A clade is another type of group that corresponds to a single lineage that is composed of a common ancestor and all its descendants
What is the Most Common Group of Trees in the World?
I remember learning at school that there were hardwood and softwood trees. I remember that on the whole the softwood trees where evergreen and hardwood were deciduous.
On the whole this seems to be true, but there are plenty of exceptions.
Of the trees I know and have heard of, or are common to the areas that I have visited in the UK and US, mainly fall in the Flowering plants and conifer divisions of the plant kingdom.
Going back to the clade grouping I mentioned earlier in the post, flowering plants has 3 clades with members that are trees.
Two of of the clades in this division contain what we know as the broadleaf or hardwood trees. They have the scientific names of Eudicots and Magnoliids.
Eudicots is the biggest clade, with it containing over 210 families. Coincidentally Eudicots contains most of the families that I am aware of.
How accurate is the grouping of trees?
Though a lot of trees, their genera, and families have common names, it is the scientific names and grouping that highlights the differences. As an example, the horse chestnut is not in the chestnut family at all.
During the research I tried to find out how many genera where in each family and how many species where within each genus.
However, there seems to be a lot of discrepances in the sources of research – trees seem to be grouped using different criteria by different organisations and people.
Moreover, differences are exaggerated by two factors.
First with modern cultivation and cross pollinating ding new species have been breed.
Second, once introduced in an area, a non-native species can cross pollinate with closely related native varieties and create new hybrids.
What are the Common Families of Trees and Their Scientific Names?
I’ve picked out some of the most common families and the genus that belong to them. Covering Hardwoods from the flowering plants (Eudicots) division and Softwoods from the conifers division.
The clickable genera have articles.
I have categorised the most common families by hardwoods or softwoods.
Hardwoods by Family with Their Scientific Names
Below are the common families and genera of the conifer division with their Scientific names:
This family includes Holly (Ilex) which is a genus of about 480 species. It is the only genius in the family that is still living.
The genus is widespread throughout the world. It includes species that are trees, but also shrubs and climbers. Holly plants have simple, alternate glossy leaves, they often have a spiny leaf edge as a common characteristic.
This family includes birches, alders, hazels, and hornbeams with 167 species in total. The majority are in the Northern hemisphere.
There are about 35 species of Alder often growing in the northern hemisphere. Most alders are deciduous. Alders commonly grow by streams, rivers and wetlands.
There are approximately 68 species of birch found mainly in the northern hemisphere. Having flowers that grow before the leaves. The bark of birches is recognisable as it often separates into thin papery pieces.
With 39 species, the majority in the northern hemisphere, hornbeams wood is well known for being hard. The species are small to medium-sized deciduous trees.
Native to the northern hemisphere, there are 15 species of the Hazel family. The hazels have simple leaves with flowers that appear before the leaves in early spring.
The Beech family has about 927 species in title and includes beeches, chestnuts and oaks.
There are just over 7 species of chestnuts. The nuts that they produce are edible. The trees are native to the northern hemisphere.
Beech are deciduous trees found in the northern hemisphere. There are in the region of 12 species in the family. Their flowers, catkins, appear shortly after the leaves in spring.
There are estimated to be about 500 species of Oak around the world. The Oak family includes both deciduous and evergreen species. North America has the largest concentration of Oak species with 90 varieties.
The Olive family has about 700 species in it, members of this family include Olive and Ash.
There are about 50 species in the Ash family the majority are deciduous, though there are some evergreen species that grow in the tropics. Unisex trees dominate the group, though with age an Ash tree can change its sex.
The Rose family contains over 4800 species. This family includes apples, pears, plums, cherries, peaches, apricots and almonds. Also in the family are rowans and hawthorns.
In the past, some botanists recognised more than a 1000 species as part of this group. Now more modern interpretation of the family has about 200 species. Another tree family native to the northern hemisphere. The name comes from the old English term for hedge – haw, a fence with thorns.
The apple family contains many hybrid and cultivated species, which includes the various varieties of apples that we eat. There are, however, somewhere between 30-50 species. The trees that grow the fruit we eat today where cultivated from a variety that is native to central Asia (Malus sieversi).
The fruit of a Pears, like apples, is sought after. There are almost 3000 know varieties of pears around the world. Pear has 39 recognised species.
This group includes the Rowan, whitebeam and mountain ash. In total, there are about 100 – 200 species, again the botanists dispute the exact number of species based on the differing definition of the genius.
The willow family includes willows, poplar, aspen and cottonwoods. There are about 1220 species in total in this family.
This group contains 25-30 species. The common names for trees in the family are Cottonwoods, aspen and poplars.
The genus has about 400 species. Willows are deciduous trees. Humans have used Willows for a long time for many uses because of their strong flexible wood.
The family includes over 138 genera and 1858 accepted species. We find the family throughout the world and include Horse Chestnut, Maples, and Lychee.
There are about 132 species with in this group, with most native to Asia. Probably most well known for the few maples that are used to make maple syrup.
This group also includes varieties known as Buckeye in the 13-19 species in the group. The group in native to the northern hemisphere. The most well known in this group is the Common Horse chestnut of conkers fame.
This family includes native species of Elms that are distributed throughout most tree zones of the world except for Australasia.
The fossil record contains the earliest examples from 20 million years ago in what is now central Asia. There are about 30 to 40 species in the group.
Softwoods by Family with Their Scientific Names
Below are the common families and genera of the conifer division with their Scientific names:
Found worldwide, the family has about 27-30 groups within it, including the junipers and redwoods. The common characteristic of this family is the orange to red-brown bark.
The coast redwood is not a genus but in fact a species. It is the sole living species of the genus Sequoia. Its common names besides coast redwood are costal redwood and California redwood. It can live a long time 1200 to 2200 years or more.
They have identified its ancestry back to the Jurassic period.
There are between 50-67 species of Juniper in the group. The highest known juniper forest is in Tibet, at an altitude of 16,000 ft (4,900m).
Again, the Giant Sequoia is the sole living species with in the Sequoiadendron group. These are the largest trees on earth. Only to be found naturally in groves on the western slopes of the Sierra Nevada mountains in California.
There are 5 species in this group, 2 from north America and 3 native to eastern Asia. The tree's ancestors are found in the fossil record of the Cretaceous period.
This family has 11 genera or groups with between 220 and 250 species. This includes genera such as firs, cedars, pines, larches and spruces.
Frequently found in mountainous regions of North and Central America, Europe, Asia and North Africa, there are 48-56 species in the group. Different from other members of the pine family by the way their needle-like leaves each attach to the branch with a suction cup like base.
Cedars are native to the mountains of western Himalayas and the Mediterranean regions. They like to grow at high altitudes, in the Himalayas 1,500–3,200m and in the Mediterranean 1,000–2,200m.
Larches are deciduous, loosing their needles in autumn, they are among the dominant trees of the very northern forests of Canada and Siberia.
The differentiator of the spruce to other pines is the way their four-sided needles attach to small peg like structures. There are about 35 species in the genus. Old Tjkko of western Sweden is a Norway spruce that is reportedly over 9550 years old.
Pine genus has over 126 species. It is the most used tree for lumber. Pines are evergreen and can live anywhere between 100 -1000 years old. The tallest is a poderosa pine in the rouge river area of Oregon at 81.79m (268.35 ft) tall.
Botanists have long struggled to classify the Douglas firs because of their similarity to other genus. Over time, we grouped the Douglas Fir with another genus of the pine family, until in 1867, when they put them in a genus of their own. There are 6 species in total in the group.
The yew family includes 6 current genus and 2 that are extinct. There are about 30 species that are living today.
We have found fossils of the Taxus in the early Cretaceous period. Yews are typically long lived and have an average girth of 5m (16 ft)
In this post I have laid out the families that I want to be covered on the site, over time I want to expand on these as I spot and see trees on my travels. I have omitted several families and genera as there are plants, shrubs and trees that I will never get to see or write about. I have included a link to a complete list here
As I researched to create the page, it is amazes me just how much diversity there is in the species of trees, the genus of Oak, for example, where there are 90 species in North America alone and even more in Mexico.
The other thing that amazes me is how botanists where, on the whole, able to categorise and group the species in the past when science was not as advanced as today. Nowadays we they have the benefits of things like DNA analysis and other tests, but much of the classification pre dates this technology.
I can’t wait to learn more about the trees that I see and aspire to see in the future.