We have now reached the social threshold from below.
Animals provide familiar examples of social organisation.
But if social mattering begins with biological value becoming relationally organised, then nervous systems should not be a prerequisite.
Plants give us a useful test.
They have no brains.
No nervous system.
No obvious centre of control.
Yet they continuously regulate their own organisation and respond to an extraordinarily varied environment.
So the question is:
What does relational significance look like in a form of life without a nervous system?
A plant begins with its own value
Consider phototropism.
A plant detects an uneven distribution of light and alters its growth so that the shoot bends towards a light source.
There is no need to imagine a plant "wanting" the light.
The point is simpler.
A difference in the environment produces a differential effect on the organisation of the plant, which changes its growth accordingly.
This is biological value in the sense with which we began.
The plant is value-sensitive without being social.
The plant lives through gradients
Plants are particularly useful because they cannot simply move away from their environment.
Their response must often be organisational rather than locomotory.
Roots grow through heterogeneous soils.
Shoots encounter changing light.
Water availability varies.
Temperature changes.
Other organisms appear nearby.
The plant alters growth, allocation and physiology in response.
Its world is therefore a field of gradients and constraints through which its organisation continually develops.
Other plants become significant
Now the interesting transition occurs.
A neighbouring plant can alter light availability.
It can compete for water and nutrients.
It can release chemicals into the soil or atmosphere.
Plants can detect a range of cues associated with neighbouring plants, including changes in light quality, root-derived chemicals and volatile organic compounds. Responses can alter growth, physiology and resource allocation.
Another organism has therefore become more than background environment.
It can become relationally significant.
The neighbour can be detected before the threat arrives
Some plant responses are especially revealing because they can occur before direct competition or damage takes place.
Volatile compounds released by plants can influence neighbouring plants, priming defensive responses or altering growth and resource allocation.
The receiver does not need to experience the original stress.
A signal from another plant can alter its own physiological organisation.
This is remarkably close to the signal-and-response pattern we saw in bacteria.
But now the organisms have much more elaborate, spatially extended organisations.
Signal is still not sign
It is tempting to call such processes communication.
That can be useful shorthand.
But our earlier distinction remains important.
A volatile molecule can engage the regulatory organisation of another plant without functioning as a symbolic sign.
The plant need not represent:
"My neighbour is under attack."
A chemical difference can simply trigger a physiological programme.
So again:
signal does not imply sign.
Meaning has not yet entered the story.
Plant relationships are context-dependent
The same signal does not necessarily produce the same response in every circumstance.
Plant responses to neighbours can depend upon species, developmental state and environmental conditions.
This matters for our concept of relational significance.
The other plant is not simply a fixed stimulus.
Its significance depends upon the relation between:
plant;
neighbour;
environment;
developmental state;
available resources.
Relational significance is therefore already contextual.
Plants also signal to organisms of other kinds
Plant signalling is not limited to plant–plant interactions.
Plants recognise signals from symbiotic microorganisms and can actively establish beneficial associations with bacteria and fungi. Root–microbe interactions involve specialised molecular signalling pathways, including signals exchanged between plants and mycorrhizal fungi or rhizobia.
This complicates the idea of the plant's "environment" still further.
The relevant world is not merely physical.
It contains other living systems whose activities can become consequential to the plant's own organisation.
The plant inhabits a relational field
We can now extend our earlier formulation.
The plant has:
biological value — its own organisation differentiates among conditions.
It encounters:
relational significance — other organisms alter those conditions in recurrent ways.
And through these interactions, it becomes embedded in a larger ecological network.
That network is not necessarily social.
But it is already a topology of biological consequence.
The root–fungus relationship is especially revealing
Mycorrhizal associations are particularly interesting because the relationship can become structurally important to both organisms.
Plants exchange signals with fungi, and the resulting association can facilitate nutrient acquisition.
The fungus is therefore neither simply "part of the environment" nor simply an independent organism encountered occasionally.
It becomes part of a persistent relationship through which each organism's possibilities are altered.
This is relational significance becoming symbiotic organisation.
Yet we should not call the plant a social organism
That distinction remains important.
Plant–plant signalling, plant–fungus symbiosis and ecological networks all involve recurrent relations.
But social mattering, as we are using the term, requires something further:
a persistent organisation of relations among distinct participants as participants.
We have not established that for plants.
And we do not need to.
The more interesting discovery is that a rich relational topology can exist without anything resembling animal society.
A different route to collective organisation
Plants therefore remind us that there is no single route from organism to collective.
Animals can coordinate through rapid nervous and behavioural responses.
Bacteria can coordinate chemically.
Plants coordinate through growth, transport, hormones and chemical signalling.
The organisation is different.
The underlying problem is similar:
How does an organism remain organised while responding to other organised systems?
Time changes the topology
Plants also introduce a different timescale.
A movement in an animal can occur in seconds.
Plant growth may unfold over hours, days or seasons.
A tree may remain in place for decades or centuries.
A relational topology need not therefore be fast to be real.
A relation can be expressed through developmental time rather than rapid behaviour.
This will become important when we turn specifically to trees.
What plants teach us
Plants give us a useful corrective.
The absence of a nervous system does not imply the absence of:
sensitivity;
regulation;
signalling;
learning-like plasticity;
relational organisation.
Nor does the presence of these capacities imply consciousness or sociality.
The categories remain distinct.
A plant can be deeply responsive to another organism without being a social participant in the human or eusocial sense.
The emerging natural history
Our sequence now looks increasingly rich:
biological value
↓
relational significance
↓
signalling
↓
recurrent interaction
↓
ecological organisation
↓
social mattering — where a stronger form of social organisation exists
The same broad organisational problem can therefore be solved in radically different biological ways.
And then there are trees
Trees make the problem still stranger.
Their bodies are modular.
Their lives are extended across enormous timescales.
Their roots interact with fungi and neighbouring organisms.
Their chemical signals can influence other plants.
Their growth records environmental history.
They participate in ecosystems that change continuously around them.
A tree therefore gives us a chance to ask not whether plants are "intelligent", but something more interesting:
What does a topology of relational significance look like when its participant grows, remembers and responds on the scale of decades or centuries?
That is where we turn next.
Trees and the Extended Topology
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