From flower to fruit and seed

The blossom and fruit chronology of the poplar

The order of what poplars form over the course of the annual cycle is as follows:

1. blossoms
2. leaves
3. fruit

blossoms

In all species of the genus Populus, the flowers are the first thing they produce in the year. These are typical kitten inflorescences that hang down as worm-shaped ears that are soft on the outside. The species that occur more frequently in Central Europe such as the trembling aspen, the black poplar or the balsam poplar begin to bloom from March or April. Depending on the location, the flowering times can be several weeks apart within poplar groups.

leaves

The foliage does not develop until after flowering, so that the poplars are initially hung with the catkins alone. In the course of April, the poplar will gradually become green.

Fruit formation with wind support

Poplars have made the wind a friend and helper in the complete generative propagation process, which is very popular among plants in general. Poplars are both wind-flowering (anemophilous) and wind-leaved (anemochoric). This means that they allow both the pollination and the spreading of the seeds to take place via air movement.

For the fertilization process, the male catkins of a poplar individual deliver their pollen to the wind. Its role is to carry the dust to female catkins on another poplar tree. After pollination, the egg cells of the female flower are fertilized within 24 hours and a seed can form.

Numerous capsule pods with 2 to 4 lobes then form all around on a female kitten flower. This is where the seeds mature to take on the important task of preserving the species. At the end of May the time has come: the capsules are spread open to release the seeds. In this phase the kittens get a felty appearance due to the opened flaps.

Now, for the second time, the wind comes into play as a supporter: it not only transports the pollen dust of the male kittens, but also the seeds of the female kittens. He hurls the seeds out of the opened capsule fruits in order to distribute them in the area and give them a chance to germinate.

Seeds with paraglider

In order to make the species reproduction as extensive as possible, the seeds are equipped with an effective flight aid: This is a tuft of white downy hair on the top. This ensures that the seeds fly as far as possible and increase the distribution radius. It also makes the seeds more buoyant, so that they can be transported much further across rivers and streams and can fulfill their reproductive function for kilometers.

Poplars produce very many of these downy seeds. This creates a downright fluff under the poplar trees in June, which looks like a summer swirl of snowflakes. So if you have poplar trees nearby, it is very possible that you will come home more often in early summer with one or two white fluff in your hair.