Possible mechanism of simultaneous emergence of purple needle-like leaves

I think that the plants are releasing hormonal signals, causing neighboring plants to produce needles simultaneously. Some desert plants may flower en masse after a specific period of time or in response to environmental triggers like rainfall or seasonal changes. Thus, this synchronization we're seeing is probably driven by intrinsic genetic and environmental factors.

Environmental cues: The emergence of the purple, needle-like leaves could be triggered by specific environmental conditions, such as changes in light intensity, temperature, or humidity.
These cues might coincide with the time frame observed by Dr Mishima . To test this possibility, the experiment could be replicated with controlled variations in environmental factors to observe if similar leaf emergence occurs.

Hormonal regulation: Plant growth and development are often regulated by various hormones.
A specific hormonal signal or interaction between different hormones may trigger the emergence of the needle-like leaves in plant X.

Testing this hypothesis could involve treating the plants with hormone inhibitors or precursors at different stages to observe their effect on leaf emergence.

Synchronization through communication: It is conceivable that the plants communicate with each other through chemical signals or other means, coordinating their growth and development. The emergence of the needle-like leaves could be a synchronized response to an external stimulus or a signal released by plant X itself. This hypothesis could be tested by isolating plant X from other plants or by conducting experiments with physical barriers between individual plants to observe if leaf emergence still occurs.

Nutrient availability: The emergence of the needle-like leaves could be related to nutrient availability or imbalances. Certain nutrients or their absence may trigger the plant's response to produce these specialized leaves. To investigate this possibility, nutrient manipulation experiments could be conducted by providing different nutrient compositions or restricting specific nutrients to determine their impact on leaf emergence.

fan198, did any of these replies help?

For whatever it's worth, I was thinking in line with @smi3 response. I initially thought pheromones, but quickly realized that's a phenomenon known in the animal kingdom, and not in plants.