Most trees flower - often annually, but some only every few years. After fertilization, fruits develop from these flowers, which are used for reproduction. However, some trees never seem to set fruit, even if they flower constantly. Why is that?
The ginkgo is one of many dioecious trees
Is there a tree that does not bear fruit?
The reason why some trees form fruit and some do not is due to their respective sex. The sex division in the plant kingdom is comparatively complicated:
- Some trees have flowers with both male and female sexual characteristics.
- Others bear both all-male and all-female flowers at the same time.
- A third group is clearly divided into purely male and purely female trees.
What does this have to do with the development of fruit? Quite simply: Purely male trees do flower, but never produce fruit. In addition, many bisexual trees are dependent on cross-pollination; H. they need a tree of the same species in the immediate vicinity so that their own blossoms can be fertilized and fruit can develop from them. This knowledge is immensely important in fruit growing, for example - without suitable pollinators, there are usually no apples, pears or cherries.
monoeciousness / dioeciousness
In botany, the different plant species are referred to as "monoecious" or "dioecious". Monoecious trees bloom with both male and female flowers, dioecious have only male or only female flowers. So there are "male" and "female" trees that need to be planted together in order to produce fruit. If, on the other hand, there is only one male tree (or even only one female with no male counterpart far and wide) in the garden, no fertilization takes place - and therefore there are no fruits either.
Examples of dioecious trees
The following tree species are typical representatives of the dioecious, although there can sometimes also be monoecious individual examples - for example in the case of the yew. Other trees, on the other hand, can change sex as needed, such as the ash (Fraxinus excelsior). All species listed are suitable for cultivation in Central European gardens.
- Ash maple (Acer negundo)
- Tree of Heaven (Ailanthus altissima)
- Andean fir / Araucaria (Araucaria araucana)
- Ginkgo (Ginkgo biloba)
- Sea Buckthorn (Hippophae rhamnoides)
- Holly (Ilex aquifolium)
- Juniper (Juniperus communis)
- Yew (Taxus baccata)
- Cake tree (Cercidiphyllum japonicum)
tips
In particular, many pome fruit varieties such as apples and pears are rarely self-fertile, but usually always need a pollinator variety. But it is not enough to simply plant any apple or pear tree next to it: not all varieties harmonize with each other.