Gardening with Wilson

Water lettuce is a fast-growing and rather invasive weed to some people and in some countries. As Singaporeans, I guess our first encounter with this plant is in our primary school curriculum where we learnt about the different types of pond plants.

The water lettuce is called as such due to its resemblence to the leafy lettuce which we eat in our salads. This plant is free-floating (because the roots do not anchor to the pond bed) with many spongy, green simple leaves arranged in a spiral pattern . The leaves are covered in very fine hairs which makes them waterproof. It can be quite fun to see water droplet sliding around on the leaves without leaving a wet trail.

Water lettuces look very nice when grown in a tub and this is, in fact, a great way to control their growth in contrast to growing them in an outdoor pond. When growth becomes excessive, I saw some gardeners taking out chains of plants linked via stolons, which got thrown away. I have seen people composting this plant before!

Botanically known as Pistia stratoites, this plant is not a member of the Asteraceae which our regular, edible lettuce belongs to. Little did we expect it to be an aroid, as members of the Araceae or the yam family are called. As an aroid, it is unusual because it doesn’t form a tuber like our edible cocoyams do. It leaves are not shield-shaped too.

So, what characteristic of the water lettuce makes it an aroid? A tell-tale sign is the minute flowers that it produces as shown in the picture below… You can see the usual aroid flower that the water lettuce produces – it features a spathe and a spadix. The flowers are so small and not easily noticeable and as a result, many individuals think that the water lettuce is a non-flowering plant!