by Robert L. Jones III
The article by Willis et al in this month’s issue of Botanical Frontiers provides an intriguing, though speculative, description of what might be the oldest sentient life form on earth. Their conclusions arise from circumstantial evidence gathered during analysis of a discovery in the northwestern wilderness of America, and here we provide a brief summary of their findings.
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The subject under consideration is a unique grove first noted for its reddish green coloration as compared with the surrounding forest. Satellite imaging and GPS readings show it to be a roughly circular patch with a diameter of over 400 meters. The constituent trees are globular in overall shape, higher than wide, somewhat tapered toward the top, and reminiscent of junipers. They are all of the same species, and save for a thick carpet of moss, there is no undergrowth.
The gray, weathered trunks are not round. Rather, they are roughly triangular in cross-section with indented sides and rounded edges. A corner of one always points directly toward that of an adjacent neighbor approximately five meters distant, and each tree is surrounded by three others in a triangular arrangement with a central point. In this way and with an arbitrary frame of reference, four trees form a conceptual unit. Sharing common points at their corners, the units fit together in a repeating pattern of hexagons.
The grove occupies a basin which sits atop an extensive aquifer as determined by GIS data. Specimens are taller with thicker boles toward the center, and one at the lowest and most central elevation is largest of all. In an eroded area encompassing a small group of trees, the upper surfaces of woody, horizontal roots are visible. Three to an individual, they extend from the corners of each trunk in remarkably straight lines, and they connect adjacent trees in the manner of stolons or runners between blades of grass, suggesting that the entire arboreal arrangement is a single organism. DNA analysis confirms this assumption.
Six slender, compound leaves radiate from the terminus of each branch. Their leaflets resemble overlapping scales which cover a stem-like petiole in whorls, and each petiole has a swelling called a pulvinus where it attaches to its branch. At low magnification under a hand lens, a round, red bump can be seen in the middle of each leaflet, accounting for the overall hue as seen from afar.
This foliage can display movement, even in the absence of detectable wind. It oscillates as if in response to the movements of investigators, and the observed behavior is putatively due to flexion and extension occurring in the pulvinus of each petiole. It is already known that pulvini are responsible for thigmonastic movements, rapid responses to touch, in plants such as Mimosa.
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Care was taken not to disturb the specimen. Only freshly fallen leaves and branches were collected for subsequent analysis.
In branch cross-sections, annual growth rings are visible to the unaided eye, and they are thin and numerous, implying that this is a slow-growing species. The bole circumference of the largest, most central tree implies that the grove could be thousands of years old.
Microscopic examination of longitudinal leaf sections provides good views of the pulvinus. The cells in this region have thinner, more flexible walls. A flexor zone on the ventral side and an extensor zone on the dorsal side of each pulvinus are readily visible. These areas are on either side of a prominent vascular bundle, and this implies a plausible mechanism based on what we know about thigmonastic movements.
As the result of a complex biochemical process, ions and water travel across cytological membranes. Since ions are charged atoms, their migration is a form of electrical activity. When ions exit, water follows by osmosis, and the cells partially collapse. When ions and water enter, swelling restores cellular shape and volume. Water simultaneously flows out of the extensor zone and into the flexor zone, and this causes the leaves to fold or close. The opposite process causes the leaves to extend or open.
Ions also move through xylem and phloem — tubular cells of the vascular tissue — that conduct food and water, and this could explain why all the leaves on an individual Mimosa plant close when only one is touched. Could such a hydraulic system of long range signal transmission be connected with multiple photoreceptors in the leaves of the grove, and are these trees exhibiting rapid, short-term movements in response to visual stimuli?
Microscopy of leaf cross-sections shows rounded epidermal bulges, each corresponding to the red bump on a single leaflet. The cells comprising these bring to mind Chlamydomonas, a unicellular alga which contains a single, large chloroplast with a red eyespot. Under the electron microscope, an eyespot appears as two layers of pigment-rich globules associated with internal membranes. Similar structures are observable in cells from the bumps on leaflets of samples collected from the grove. The putative eyespots are enlarged compared to those of Chlamydomonas, and if they are similarly responsive to light, that would make them constituents of the only known multicellular visual organs in a plant.
Multiple branches of vascular bundles infiltrate each bump. Vascular tissue in plants and nerve and muscle tissue in animals all exhibit electrochemical activity. Are the bumps, vascular systems, and pulvini of the trees in the grove analogous to a neuromuscular system? Furthermore, is the canopy a retinal analogue which simultaneously receives stimuli in multiple directions from within and outside its confines?
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The ability to process that much visual information would imply intelligence. The human brain contains over 100 trillion synapses between its neurons, and their three-dimensional arrangements form the neurological pathways involved in thinking. By comparison, the grove is composed of thousands of interconnected trees, each with uncounted branches and even more leaves covered in leaflets with putative eyespots connected to an intricate network of vascular tissue.
In addition to all this data and supposition, there are problematic and abstract questions to answer. If it can distinguish between itself and its environment, what might the grove think about? Is it wise, or is it more like an infant examining its surroundings from a cradle? The vast majority of our world would be inaccessible. Might this result in loneliness and under-stimulation?
Perhaps not. Beneath a changing sky and with the movements of animals within or near its borders, its great lifespan could have afforded more time to appreciate less in greater detail. Humans are aware of the telescopic effect that aging has on the perception of time, but the grove is far older. Several of our generations, might seem but a momentary association to such a being. One is tempted to imagine the grove thinking through qualitative impressions rather than language or mathematics. In this sense, it could be wise.
Despite our increased understanding of the chemical and morphological details of thought and memory, we are still at a loss to explain the subjective nature of consciousness. Controlled experiments demonstrating causal relationships are yet to be performed on the grove, but these would require violating its structural and functional integrity, all of which could amount to vivisection and physiological disturbance without the subject’s consent.
Willis at al report that the leaves of a branch terminus close around a human hand extended into their proximity. Anthropomorphic reasoning suggests a form of interspecific handholding, six digits to five, and perhaps this metaphor is as good a start as any at establishing communication.
— The editors, Botanical Frontiers
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Bio:
Robert L. Jones III holds a doctorate from Indiana University and is Professor Emeritus of Biology at Cottey College in southwestern Missouri, USA. His speculative poems and short stories have appeared in The Magazine of Fantasy and Science Fiction, Star*Line, Heart of Flesh Literary Journal, and previously in Sci Phi Journal.
Philosophy Note:
Physical mechanisms of thought have been of interest to me for years. The same is true of plant responsiveness, and I wanted to combine findings from both areas into a reasonably plausible model for plant consciousness in a novel and imaginary species. Fictional nonfiction in the guise of a brief scientific review seemed the best format to use in this endeavor.
