The Himalayas are an awe-inspiring natural wonder that deserves the title of “epic”. These towering peaks boast some of the highest points on Earth and are renowned for the formidable challenges they present to adventurers from around the globe. Despite their elevation, life thrives on these mountains, including a fascinating plant species that is related to rhubarb, a common garden and pie ingredient in more hospitable climates. This peculiar plant can be found among sprawling shrubs and diminutive herbs, making the Himalayas even more intriguing.
Allow me to introduce you to the remarkable Rheum nobile, also known as the noble rhubarb. This plant truly lives up to its noble name, as it grows in some of the harshest conditions on earth. Found at elevations ranging between 13,000 and 15,000 feet (4000–4800 m), this species is a true survivor. Despite facing extremely low temperatures and damaging UV radiation, Rheum nobile can grow up to an impressive height of 6 feet, making it the tallest plant for miles around. While most plants in alpine zones grow prostrate over the ground, taking refuge behind rocks, Rheum nobile stands tall and proud. It’s no wonder this member of the buckwheat family has earned its noble status.
The most remarkable aspect of this particular plant is its striking spire made up of translucent bracts. These unique leaves are modified and lack chlorophyll, meaning they don’t contribute to photosynthesis. Instead, their primary role is to provide protection and warmth for the plant. Hidden behind the bracts are the plant’s flowers, which would be susceptible to damage from the elements without the protective shield. The bracts contain specialized pigments that filter out harmful UV wavelengths while creating a favorable environment for the flowers and seeds to grow. 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 the surrounding environment. This provides a significant advantage to the plant’s reproductive process. However, the lack of pollinators at such heights presents another challenge for the plant. To overcome this, Rheum nobile utilizes both visual and chemical cues to attract pollinators. Its unique appearance stands out in the bleak surroundings, while its chemical signals entice pollinators to come closer.
The Rheum nobile plant has established a mutually beneficial relationship with fungus gnats that reside at high altitudes. The plant produces a unique chemical compound that lures in the 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 that is protected from the harmful effects of UV radiation.