Spider-Man plant found in Pakistan, ejects cobweb-like threads

Spider Man plant found in Pakistan, ejects cobweb like threads

CAMBRIDGE (Web Desk) – Like the movie version of Spider-Man who shoots spider webs from holes in his wrists, a little alpine plant has been found to eject cobweb-like threads from tiny holes in specialised cells on its leaves.

It s these tiny holes that have taken plant scientists by surprise because puncturing the surface of a plant cell would normally cause it to explode like a water balloon.

The small perennial cushion-shaped plant with bright yellow flowers, Dionysia tapetodes, is in the primula family and naturally occurs in Turkmenistan and north-eastern Iran, and through the mountains of Afghanistan to the border of Pakistan. What makes it unusual is its leaves, which are covered in long silky fibres that resemble fine cobwebs called  woolly farina .

Quite a few of its primula relatives have leaves coated with a fine powder consisting almost entirely from flavone, which is a class of flavonoid. Flavonoids are small specialised molecules involved in plant metabolism and are recognised for their anti-inflammatory and antioxidant properties. But this Dionysia species does not have flavone powder on its leaves, instead it has very fine wool just 1-2 microns thick - far thinner than a human hair, which is about 75 microns.

As part of an ongoing collaboration between the University of Cambridge s plant science research institute Sainsbury Laboratory Cambridge University (SLCU) and Cambridge University Botanic Garden (CUBG), Dionysia was selected from the Botanic Garden s living collection of 8,000 cultivated plant species to be analysed at SLCU s Microscopy Core Facilities.

"The woolly farina threads seem to cover the entire leaf surface with long threads even connecting leaf-to-leaf," said Paul Aston, who is the Botanic Garden Alpine and Woodland Supervisor. "Nobody knew what this wool was or how it was made and so we thought that this would be an interesting specimen to study. There are many things that plants make that we do not yet know about - this is especially true for alpine plants where we see many unusual adaptations to the harsh high altitude environments they live in."

Samples were analysed using advanced light and electron microscopes, which revealed the micron-diameter wool had distinct parallel grooves running along their length. But the most surprising observation was how the wool was emerging from the leaves.

"The leaves are covered in tiny hairs called trichomes. Each trichome has a spherical shaped glandular cell at the end - like a stalk with a single round cell at the tip - and we could see the threads emerging straight out of the glandular cell," said Dr Raymond Wightman, who is the Microscopy Core Facility Manager in the University of Cambridge s Sainsbury Laboratory. "But we know that plant cells are surrounded by a cell wall that protects and retains pressure within the cell. Poking holes through the cell membrane and cell wall would cause the cell to burst - like puncturing a water balloon."