An MRI scans brain activity and an EEG scans brainwaves.
You can get bsic EEGs for about
£1000 and while an MRI scanner would run into the £10,000s.
EEGs work by:
QUOTE
measuring summated activity of post-synaptic currents. An action potential in a pre-synaptic axon causes the release of neurotransmitter into the synapse. The neurotransmitter diffuses across the synaptic cleft and binds to receptors in a post-synaptic dendrite. The activity of many types of receptors results in a flow of ions into or out of the dendrite. This results in compensatory currents in the extracellular space. It is these extracellular currents which are responsible for the generation of EEG voltages. The EEG is not sensitive to axonal action potentials.
So unless this makes
any sense to you (which I doubt given the fact that you think that flora have brains) I don't think you'd be able to build one, no.