The Himalayas possess a breathtaking beauty that truly deserves the epithet “epic.” These majestic peaks claim some of the highest altitudes on Earth and are renowned for the formidable challenges they present to adventurers worldwide. Surprisingly, life flourishes amidst their towering heights, including a captivating plant species closely related to rhubarb, a common ingredient in gardens and pies in more hospitable climates. This peculiar plant can be found amidst sprawling shrubs and diminutive herbs, adding to the allure of the Himalayas.
Allow me to introduce you to the extraordinary Rheum nobile, also known as the noble rhubarb. This plant lives up to its noble name by thriving in some of the harshest conditions on the planet. Found at elevations ranging between 13,000 and 15,000 feet (4000–4800 m), this species is a true survivor. Despite enduring extremely low temperatures and damaging UV radiation, Rheum nobile can reach an impressive height of 6 feet, making it the tallest plant for miles around. While most plants in alpine zones grow low to the ground, seeking refuge behind rocks, Rheum nobile stands tall and proud. It’s no wonder this member of the buckwheat family has earned its esteemed reputation.
The most remarkable feature of this particular plant is its striking spire composed of translucent bracts. These unique leaves are modified and lack chlorophyll, which means they don’t contribute to photosynthesis. Instead, their primary function is to provide protection and warmth for the plant. Concealed behind the bracts are the plant’s flowers, which would be vulnerable to damage from the elements without this protective shield. The bracts contain specialized pigments that filter out harmful UV wavelengths while creating a favorable environment for the flowers and seeds to flourish. Essentially, this plant creates a greenhouse-like atmosphere for itself.
Due to its high elevation, Rheum nobile experiences temperatures that can be up to 10 degrees warmer than its surrounding environment. This offers a significant advantage to the plant’s reproductive process. However, the absence of pollinators at such heights presents another challenge for the plant. To overcome this, Rheum nobile employs both visual and chemical cues to attract pollinators. Its distinctive appearance stands out amidst the desolate surroundings, while its chemical signals entice pollinators to approach.
The Rheum nobile plant has established a mutually beneficial relationship with fungus gnats that inhabit high altitudes. The plant produces a unique chemical compound that entices female fungus gnats. These females lay their eggs in the plant’s developing seeds but also end up pollinating more flowers than they parasitize. It’s a delicate balance that has been struck within this mountainous environment. In exchange for pollination services, the fungus gnats have a safe and warm location to raise their offspring, shielded from the harmful effects of UV radiation.