In late spring, the infructescence develops on the catkins of the poplar. Anyone who has ever walked through a poplar forest in early summer knows what happens a little later: It's raining downy seeds.
The seeds of the poplar grow in capsule fruits
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. Flowers
2. Foliage
3. Fruits
blossoms
With all species of the genus Populus, the flowers are the first thing they produce in the year. These are typical catkin inflorescences that hang down as worm-shaped spikes that are soft and downy on the outside. The species that are more common in Central Europe, such as the quaking 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, even within groups of poplars.
leaves
The foliage only develops after flowering, so that the poplars are initially only hung with catkins. In the course of April, the poplar will gradually green up.
Wind assisted fruiting
Poplars have made the wind their friend and helper in the complete generative propagation process, which is generally very popular among plants. Poplars are both anemophilous and wind-blooded (anemochor). This means that they use air movement for both pollination and seed dispersal.
For the fertilization process, the male catkins of a poplar individual hand over their pollen dust to the wind. Its role is to carry the dust to female catkins of another cottonwood tree. After pollination, the egg cells of the female flower are fertilized within 24 hours and a seed can form.
Numerous fruit capsules with 2 to 4 lobes then form all around a female catkin 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 open flaps give the kittens a felt-like appearance.
Now the wind comes into play as a supporter for the second time: it not only transports the pollen dust of the male catkins, but also the seeds of the female catkins. He throws the seeds out of the open 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 far-reaching as possible, the seeds are equipped with an effective flight aid: This is a tuft of white downy hairs on the upper side. This ensures that the seeds fly as far as possible and increase the radius of distribution. It also makes the seeds more buoyant, so that they can be transported much further down rivers and streams and fulfill their reproductive function for kilometers.
Poplars produce a great many of these downy seeds. This creates a veritable flurry of fluff under the poplar trees in June, which looks like a summer whirl of snowflakes. If you have poplar trees nearby, it is quite possible that you will come home in early summer with one or two fluffy white fluffs in your hair.