The lotus is a remarkable plant. I’m referring to Nelumbo nucifera, which is native to Asia and sacred to both buddhists and Hindus. (It’s related to the American lotus, N. lutea, but not to the lotus that appears in ancient Egyptian images – that’s Nymphaea lotus. Plants in the Nymphaea genus are more commonly referred to as waterlillies in the UK.)
The lotus has a very wide native distribution across Asia, and has made its way further afield due to its beauty and utility – every part of the plant is edible. Seeds or ‘nuts’ can be harvested from the huge seedpods during the summer, and are good sources of protein and minerals (they are also used in Chinese medicine). Lotus seed paste, usually sweetened, finds its way into the centre of Chinese pastries.
Lotus root (actually a rhizome) is a delicacy in Chinese cuisine. A good source of fibre and vitamin C, it is usually served in slices which display a fascinating pattern of holes. These are caused by the long air channels that run the entire length of the underwater rhizome.
Young leaves are edible, but Chinese cooks also harvest the more mature leaves, and use them as a wrapping for sticky rice with chicken and mushroom; the leaves impart a subtle tea-like flavour. Across Asia, cuisines make use of the young flowers and flower stems. All of these edibles can be preserved by drying.
The bounty of the lotus is remarkable, but that’s not why it’s sacred. It is revered as a symbol of purity, rising pristine from the mud. It’s a neat trick that I, as a gardener, would love to replicate. The closest that humans can get is a nice wax jacket!
The underlying science behind the Lotus Effect, as it is now called, wasn’t explained until the invention of the scanning electron microscope, in the 1970s. Lotus leaves are made hydrophobic but the microstructure of their surface. So not only do water droplets not wet the leaves, but they take dirt with them as they roll off. There are other plants that exhibit the same effect, and you may have some of them in your garden. You may have noticed dew or raindrops looking unusually spherical on your nasturtium leaves – that’s the lotus effect. The dense hairs on the leaves of Lady’s Mantle exhibit the same property, as do lupins, Oriental poppies, sweet peas, Aquilegea, Colocasia esculenta, Canna indica, and brassicas. When you going looking for it, it turns out that the Lotus Effect is quite widespread. Scientists speculate that this self-cleaning ability is a defence against pathogens, but plant’s physical features often serve more than one purpose.
So great is the power of the Lotus Effect, that scientists are investigating how to recreate it. One lovely example I found was researchers investingating whether a hydrophobic coating could protect the stonework of York Minster. Various surface treatments, coatings, paints, roof tiles, fabrics and have been created that stay dry and are self-cleaning. (Are the plant pots of the future self-cleaning? Let’s hope so!) Scientists have also used very strong laser pulses to etch a hydrophobic surface onto metals.
It is possible to grow Nelumbo nucifera in the UK, and the RHS have cultivation details on their website. Those of us without large ponds will just have to marvel at the raindrops on nasturtiums and cabbages, instead.
Neinhuis, C., & Barthlott, W. (1997). Characterization and distribution of water-repellent, self-cleaning plant surfaces. Annals of botany, 79(6), 667-677.
A Fritsch, GR Willmott & M Taylor (2013) Superhydrophobic New Zealand leaves: contact angle and drop impact experiments, Journal of the Royal Society of New Zealand, 43:4, 198-210, DOI: 10.1080/03036758.2013.782879.
Vorobyev, A. Y., & Guo, C. (2015). Multifunctional surfaces produced by femtosecond laser pulses. Journal of Applied Physics, 117(3), 033103.
This post was produced in collaboration with Equestrian Co.