It changed color and also changed gender...

Welcome to Northern Plants. Today I will introduce you to the blackberry, Causonis japonica .

Although the name of blackberry contains both "wu" and "berry", it has nothing to do with black plum, strawberry, etc. The most important word in its name is "蔹", which refers to some vines of the grape family, to which blackberry belongs .

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Common grape plants include various creepers, such as Parthenocissus heterophylla, Parthenocissus quinquefolia, etc. The appearance of the blackberry is particularly similar to the five-leaf parthenocissus Parthenocissus quinquefolia. They rely on tendrils opposite to the leaves to entwine and climb. However, the leaf sizes of these two plants are very different. You can see the comparison between them and my left hand.

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Moreover, the leaves of the quinquefolia are palmate compound leaves, and each leaf generally has 5 leaflets, which are connected at the base, a bit like a human palm.

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Although the leaves of the blackberry also have 5 leaflets, they are not all connected together. Instead, they are first divided into three forks, with a leaflet extending from each of the left and right forks. This arrangement is called bird's foot arrangement .

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Since blackberry belongs to the grape family, can its fruit be eaten as a fruit like grapes? Well... this... really can't. Although its black berries are not poisonous, they are not delicious. However, its flowering and fruiting process is quite interesting and worth observing, because its flowers can "change sex".

The flowers of blackberry are very small, only a few millimeters in diameter, with a flat round structure in the center called a disk, on which the petals, stamens and pistils all grow.

Image taken from video

Image taken from video

On the day of flowering, four small green petals unfold, the disc is orange, filled with nectar and swaying, which is especially attractive to insects for pollination. At this time, the stamens have matured and can release pollen, but the pistils have not yet fully developed and cannot accept pollen normally. Functionally, the flowers of blackberry are male flowers when the disc is orange .

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A few hours after flowering, the petals will curl up and fall off along with the stamens that have finished spreading pollen. The pistil begins to develop. Generally, on the second to third day after flowering, the pistil will be able to accept pollen. At the same time, the disk will turn from orange to pink , telling insects: My flower has no nectar anymore, so you don’t need to waste too much time on me. Just pass the pollen to me and you can leave. Go to the newly opened orange flower next to it to collect nectar.

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Functionally, when the disc turns pink, the flower of the blackberry is female .

Image taken from video

Generally speaking, after successful pollination, the flowers of plants should slowly develop into fruits. However, some blackberry plants, although they bloom well and are pollinated by insects, never bear fruit. They are likely to be natural triploids, and the pollen has no reproductive capacity. In this case, the blackberry is just giving the insects a feast for nothing.

Author: Wu Changyu

Review | Wang Kang, Director of the Science Museum of the National Botanical Garden

The video is produced by Science Popularization China-Creation Cultivation Program

Text content is organized according to the video

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