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Certain species of wild oats have a special seed dispersal system that
looks as if the seeds are walking on the ground looking for suitable
soil to take root in.
Modern-day oats (Avena sativa) have been drastically altered through
domestication and are entirely dependent on humans for their survival.
Not only do they need to be drilled into the soil, but the seeds remain
attached to the panicle to make them easier to harvest and minimize seed
losses. Wild oats, on the other hand, are a completely different story.
They have evolved highly specialized anatomical features that actually
assist the spikelets housing the seeds to move on the ground in search
of suitable rooting soil. This amazing ability has won the plants
several nicknames, including “Animated Oats” and “Animal Oats”.
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Once the oat spikelets fall to the ground, two long twisted awns with a
fixed 90-degree bend at the mid-point start to rotate, making it seem
like the structure is moving consciously. It is only an illusion, as the
movement is a purely physical process affected solely by daily wet-dry
cycles, and not some plant consciousness.
According to this informative video I found while researching this
evolutionary trait, in the evening, as the sun sets, moisture from the
air condenses onto the spikelet surfaces. The part of the long, bent
awns closest to the seeds are made of twisted tissue, and one side
absorbs moisture and swells, while the other remains dry. This causes
the awns to unwind and push against whatever surface they are leaning
against, in an action so strong that it actually causes the spikelet to
move.
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But even though this “walking” is not conscious – the spikelet will move
the same way under the right weather circumstances even if the seed
inside is dead – it serves a very specific purpose. The constant
movement facilitated by the daily wet-dry cycle increases the chances of
the spikelet ending up in the shadow of a stone or in a soil crack,
somewhere with increased moisture that can help the germinating embryos
survive.
The movement of animated oats is just one of the fascinating
evolutionary traits we’ve featured on Oddity Central over the years.
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