The Kórnik Arboretum belongs to the Institute of Dendrology of the Polish Academy of Sciences. A rich collection of trees and shrubs from the temperate zone of the northern hemisphere has been collected here. Particularly numerous species represent the woody flora of eastern Asia (Japan, Korea, China) and North America. The collections also include trees and shrubs from the mountainous areas of Central Asia and the Caucasus. The number of species and varieties in the arboretum's collections is currently approximately 3,500.
Particularly richly represented are birches (Betula), drywoods (Lonicera), poplars (Populus), lilacs (Syringa), meadowsweets (Spiraea) and coniferous trees and shrubs (firs, spruces, pines, yews, thujas, junipers and others). The arboretum also has a rich collection of ornamental shrubs (forsythias, apple trees, cherries, rhododendrons, rhododendrons, shrubs, magnolias, jasmine trees and others).
The creation of such a rich dendrological collection is the result of the activities of several generations of people associated with Kórnik. In the second half of the 18th century, Teofila Potulicka née Działyńska arranged a French-style park next to the castle with clipped hedges, stone figures of animals and water fountains. The next reconstruction of the park in the years 1826-1860 was carried out by Tytus Działyński, who began collecting a collection of trees and shrubs following the example of similar objects in England, France and Germany. The park was rebuilt in the then new landscape style, also known as the English style, which is characterized by a free arrangement of groups of trees, vast areas of meadows and distant perspectives. Kórnik Park has preserved many elements of such garden architecture to this day.
Tytus Działyński and then his son Jan brought to Kórnik seeds and seedlings of numerous trees and shrubs, most often unknown in Poland at that time, from nurseries and the most famous horticultural establishments in England, France, the Netherlands and Germany, spending considerable sums for this purpose. In particular, Jan Działyński gathered here a collection of approximately 1,500 species in the years 1860-1880. These were undoubtedly the richest dendrological collections in Poland and one of the largest in Europe. Jan Działyński is also the creator of a wonderful park in Gołuchów, where he also founded a very rich arboretum with numerous species of foreign trees and shrubs. Tytus and Jan Działyński created a collection of trees and shrubs in Kórnik with the express purpose of establishing a higher forestry and horticultural school here. After the death of Jan Działyński (1880), Kórnik became the property of Władysław Zamoyski (1853-1924), who, before his death, donated the Kórnik estate together with priceless museum collections, a library and a park to the Polish nation, creating the "Zakłady Kórnickie" Foundation. According to the founder's will, the dendrological collection was to be used for scientific research in forestry and horticulture.
From 1926, the "Kórnicki Gardens", as the park, nurseries and orchards were then called, were managed by Antoni Wróblewski, an outstanding dendrologist, gardener and botanist. He quickly rebuilt the neglected park and gathered a collection of trees and shrubs, which before World War II numbered 3,000 species and varieties. He introduced full documentation of the dendrological and pomological collections so that they could be used for scientific research. Kórnik nurseries, known for producing a wide range of rare trees and shrubs, were enlarged. New or little-known trees and shrubs were popularized in the country through nurseries. Among others, the following species have been introduced into cultivation in Poland: Korean fir (Abies koreana), golden arborvitae (Thuja occidentalis 'Aurescens'), Veitch fir (Abies veitchii), Chinese quill (Kolkwitzia amabilis), purple apple trees (Malus purpurea) and many others. Already in the interwar period, A. Wróblewski tried hard to organize a scientific institute in Kórnik that would study trees and shrubs. However, the efforts did not bring much results due to lack of funds. Despite this, a project was created to organize the Tree and Forest Research Institute, which was fully implemented in the post-war period. In 1952, the then Department of Dendrology and Pomology was taken over by the Polish Academy of Sciences. The Kórnik Arboretum, as an integral part of this Department and an important scientific research base, has entered a period of new and dynamic development. The area of the Arboretum has been enlarged and now amounts to 50 ha. Collections of some types have been enlarged, mainly ornamental shrubs (rhododendrons, heather and briars, apple trees, lilacs, dwarf varieties of spruces) and fast-growing trees (poplars and willows). A new dendrological collection was established in the Zwierzyniec experimental forest (on the opposite shore of Lake Kórnickie). There is a collection of some conifers (firs) and shrubs from the heather family (rhododendrons). Due to lack of space in the old Arboretum, the collection of ornamental shrubs was moved outside its boundaries to experimental areas. Here, there is an enlarged collection of ornamental apple trees, lilacs, forsythia, meadowsweets and other types. The trees and shrubs collected in the Kórnik Arboretum collection are the subject of multidirectional research conducted by the Institute of Dendrology. First of all, these are works in the field of systematics, acclimatization, physiology and genetics. The results of this work are used in forestry, horticulture (planting trees in cities and housing estates) and increasingly serve to protect the environment and the idea of planting trees in the country. The Kórnik Arboretum plays an important role in the process of introducing trees and shrubs. There is a facility where new or little-known species and varieties undergo the first period of adaptation to climatic conditions that are different for them. Based on the first observations of plants in the Arboretum, they can be recommended for cultivation in Poland and their requirements and economic usefulness can be determined. The Kórnik Arboretum grows wonderful specimens of rare trees and shrubs, as well as numerous old domestic trees. The most beautiful ones include huge beeches, lindens, oaks, spruces, firs, poplars and elms. The oldest linden trees in the main avenue running from the castle towards the south are considered to be the oldest. They are about 300 years old. The age of the huge beech tree near the moat surrounding the castle is estimated at 250 years. An interesting example of a park alley is a road densely planted with linden trees in the eastern part of the Arboretum. It was founded around 1890 and is called Aleja Generałowej Zamoyska (the mother of the founder - Władysław Zamoyski).
Also worthy of special attention are wonderful specimens of foreign trees planted in the times of Tytus and Jan Działyński, i.e. 120-150 years old. These are primarily black walnut trees (Juglans nigra) near the castle, ginkgo bilobas (Ginkgo biloba) and ginkgo trees (Gymnocladus dioicus) - at the entrance gate to the castle, swamp cypress trees (Taxodium distichum) in the meadows in the central part of the arboretum, tree magnolias (Magnolia acuminata), numerous plane trees (Platanus aceriphotia), walnut trees (Carya laciniosa, C. cordiformis, C. ovata), Greek firs (Abies cephalonica) and others.