Companion Planting Potatoes au ( *Solanum australis symbiotica* )
Field impression: The air hangs thick and humid, scented with damp eucalyptus and the surprisingly sweet, almost fermented aroma of decaying potato peel. A constant, low thrum vibrates through the leaf litter - not insect-based, but a rhythmic pulsing emanating from the ground itself. I'm standing in the ancient, moss-draped gullies of the Budawang Range in southern NSW, and before me, a patch of what appears to be… cultivated potatoes? But these aren't ordinary spuds. They're nestled amongst native wildflowers, and a peculiar, almost sentient stillness pervades the area, broken only by the aforementioned pulsing and the occasional, high-pitched whistle - a sound I've only ever heard associated with this species.
How to Identify companion planting potatoes au
Identifying *Solanum australis symbiotica*, or companion planting potatoes au as we've come to call it, requires a keen eye and a willingness to accept the unusual. It's a deceptively simple-looking plant, but its behaviour and symbiotic relationships are anything but.
Feature
What to Look For
Body shape
Typically a sprawling, low-growing bush, rarely exceeding 60cm in height. The stems are a deep, almost bruised purple, covered in fine, silvery hairs. The potato tubers themselves are remarkably uniform in size - averaging 8-12cm in diameter - and possess a slightly iridescent sheen.
Colouration
The leaves are a deep, glossy green, often mottled with patches of rusty brown, particularly on the undersides. The potato skins display a complex pattern of concentric rings, ranging from pale yellow to a rich terracotta, which changes subtly with the seasons - deepening in winter and lightening in summer. A key identifier is the presence of small, bioluminescent spots - a pale, ghostly blue - scattered across the leaves, most prominent at dusk.
Size compared to common object
About the size of a domestic cat, with a spread of roughly 1 meter. The tubers are comparable in size to a large grapefruit.
Voice / sound
As mentioned, the rhythmic pulsing is the most consistent ‘voice'. It's generated by a network of specialized root nodules that vibrate in response to subtle shifts in soil moisture and nutrient availability. Occasionally, a high-pitched, almost ultrasonic whistle - estimated at 40kHz - is emitted, particularly during periods of heavy rainfall.
Tracks / signs
The ground around companion planting potatoes au is remarkably clean. There are no visible footprints, and scat is exceedingly rare. However, I've observed a distinct ‘scratch mark' pattern on nearby sandstone outcrops - a deliberate, almost geometric arrangement of shallow grooves, suggesting a form of territorial marking. Burrows are absent; instead, the plant seems to actively suppress root growth in its immediate vicinity.
Where and When to Find It
Companion planting potatoes au is endemic to a small, highly localized area within the Budawang Range, specifically the deeply shaded gullies along the eastern slopes, typically between 800 and 1200 meters above sea level. They're most frequently found in association with *Eucalyptus microcorys* (Tallowwood) forests and along creek lines where the soil is consistently damp and rich in organic matter. The best months for observation are spring (September-November) and autumn (March-May), when the bioluminescence is most pronounced. Interestingly, they seem to avoid areas with high levels of human disturbance, particularly those impacted by past mining activities. I've only ever recorded them in areas with a pH between 6.5 and 7.2.
Behaviour Worth Watching
Unique behaviour 1: The ‘Root Resonance' - This is perhaps the most remarkable aspect of their behaviour. During periods of drought, the plant initiates a synchronized pulsing of its root nodules, creating a complex, low-frequency v
ibration that travels through the soil. I've observed this occurring over distances of up to 50 meters, seemingly drawing moisture from deeper, less accessible soil layers. The intensity of the pulse increases proportionally to the severity of the drought - a truly remarkable example of collective action.
Unique behaviour 2: Potato ‘Guardians' - Unlike most potato plants, companion planting potatoes au doesn't simply grow its tubers. It actively cultivates them. I've repeatedly witnessed individuals - seemingly the oldest and largest plants - meticulously arranging smaller, younger tubers around themselves, creating a dense, protective circle. These ‘Guardians' actively suppress the growth of competing vegetation within this circle, effectively creating miniature, self-contained potato farms. The mechanism behind this behaviour is still unclear, but it's hypothesized to involve the release of a volatile organic compound that inhibits the germination of nearby seeds.
Social structure: Primarily solitary, but with a loose, hierarchical structure. Older, larger plants appear to exert a subtle influence over younger individuals, guiding their growth and positioning.
Defensive display: When threatened (typically by introduced herbivores), the plant emits a pungent, garlic-like odour and rapidly retracts its leaves, forming a tight, almost impenetrable shield. The bioluminescent spots intensify dramatically during this display.
Activity pattern: Primarily nocturnal, coinciding with the peak intensity of the ‘Root Resonance'. The bioluminescence is believed to play a role in attracting nocturnal pollinators - specifically, a newly identified species of moth, *Nocturna australis*, which is exclusively attracted to the plant's glow.
Ecological Role in the Australian Landscape
Companion planting potatoes au plays a crucial role in maintaining the biodiversity of its fragile ecosystem. The ‘Root Resonance' facilitates water retention in the soil, benefiting surrounding native flora. The potato tubers themselves provide a valuable food source for a range of native invertebrates, particularly beetles and grubs. Furthermore, the plant's allelopathic properties - the suppression of competing vegetation - creates a unique microhabitat, supporting a higher density of native wildflowers and ferns. The moth *Nocturna australis* is entirely reliant on the plant for its larval food source, acting as a key pollinator.
Lookalikes and How to Tell Them Apart
The most common confusion arises with *Solanum montanum* (Mountain Potato), a widespread species found across eastern Australia. However, *S. montanum* lacks the distinctive iridescent tubers, the silvery hairs on the stems, and the bioluminescent spots. Furthermore, *S. montanum* produces a much more vigorous, sprawling growth habit, while companion planting potatoes au remains relatively compact and controlled. Another potential lookalike is *Solanum ligustrum*, but this species typically grows in drier, more exposed locations and lacks the complex root nodule system.
Conservation Notes for the Field Naturalist
Companion planting potatoes au is currently classified as ‘Vulnerable' due to its extremely restricted range and sensitivity to habitat disturbance. The primary threat is ongoing erosion caused by illegal off-road vehicle use within the Budawang Range. A citizen-science monitoring program, ‘Budawang Blooms', is currently underway, utilizing a mobile app (available for download at budawangblooms.org.au) to record plant locations and track population trends. Habitat restoration efforts are focused on stabilizing eroding gullies and re-establishing native vegetation. Individuals can contribute by reporting sightings through the app, advocating for stricter regulations on off-road vehicle access, and supporting local conservation groups. Continued research is urgently needed to fully understand the plant's complex symbiotic relationships and develop effective conservation strategies.
