Things to know about conifers

The leaves of trees change color in autumn and fall off at some point - we learn that from an early age. But the fact that the needles of conifers are also leaves and why they do not fall off every autumn in the vast majority of species is usually of less concern to us. Reason enough to take a closer look at this interesting group of species and to think about these and other questions, for example how the needles actually survive the winter or why the Scots pine is so common in Berlin.

Conifers are gymnosperms

Botanically, conifers differ from most deciduous trees by being gymnosperms. This means, that the ovules of conifers are not enclosed in female leaf organs as in angiosperms, but lie exposed on them. The flowers are either purely female or purely male and usually sit very close together in groups of the same sex. This is how the cone, typical of conifers, is formed. It is therefore common to speak of male and female flower cones. These are usually on the same tree

False berries

When the female cones are mature, the cone scales lignify, spread open and the winged seeds can fall out. Depending on the species, months to several years may elapse between fertilization and cone maturity. In some conifers, such as common juniper or common yew, the scales may remain fleshy or even be replaced by a fleshy seed coat. Although these seed coats look like berries, botanically they are neither berries nor fruits.

Needles instead of foliage leaves

The leaves of most conifers, unlike typical deciduous leaves, are long, thin and needle-shaped. Somewhat different in shape are the leaves of the cypress family, which includes the thujas (for example, northern whitecedar) and the sequoias (for example, giant sequoia). They have scale-like leaves. Although needle leaves look different from deciduous leaves, they perform the same functions such as photosynthesis and regulation of water balance.

Evergreen needles bring benefits and challenges

But there is one big difference: the leaves of almost all conifers are evergreen, which means they remain on the tree all year round. Depending on the species, the needles remain on the plant for two to 40 years until they fall off year-round at the end of their life. Evergreen conifers can thus save important resources, but they also face special challenges.

Adapted to dry and cold conditions

For example, because frozen soils can make it difficult to absorb water in winter, coniferous leaves have adaptations to drought. Compared to deciduous leaves, they have a much smaller surface area, are more robust, and are surrounded by a wax layer to prevent desiccation and frost damage. In addition, when it is cold, evergreen conifers develop glycol-like substances that lower the freezing point of the water contained in the needles, as in modern antifreeze. However, there are also coniferous tree species, such as the European larch, whose needles change color like leaves in the fall and then fall off.

Conifers grow almost everywhere and dominate in the north

This special way of life enables evergreen conifers to grow even in cooler locations with dry and nutrient-poor soils and thus to cover a large area of distribution. Conifers are therefore found almost everywhere in the world and in their northern habitats, such as the boreal coniferous forest, they are even the dominant plants. But Berlin is also unthinkable without one conifer in particular - the Scots pine. This is no coincidence, as it is one of the tree species most frequently grown for timber in Germany. Berlin's sandy and dry soils are an additional advantage for the Scots pine, as it faces less competition from deciduous trees. Particularly in the forests of the tree-rich peripheral districts, such as Tegeler Forst or Grunewald, it is therefore a characteristic feature of the landscape.