SINGAPORE - A humble aquatic plant had its day in Parliament this week as MPs sprinkled their speeches liberally with "duckweed" while sparring about the Non-Constituency MP (NCMP) scheme and whether a vacated NCMP post should be filled.

There was so much duckweed floating around, it even found its way into an amended motion on whether to allow the opposition Workers' Party (WP) to nominate another candidate to fill its third NCMP post which Ms Lee Li Lian turned down.

Curious now about the tiny plant? Read on.

1. So, MPs debated about duckweed?

No, not really. "Duckweed" was used as an analogy for NCMPs.

WP chief Low Thia Khiang used it on Wednesday (Jan 27) when reporters quizzed him about Prime Minister Lee Hsien Loong's proposal to give NCMPs equal voting rights as MPs.

Mr Low compared NCMPs to "duckweed on the water of the pond". This was to illustrate his view that they lack both political muscle and grassroots grounding.

"You don't have roots, unlike elected MPs, where you have a constituency, run a town council, and you get close in touch with your residents. You can sink roots there," he said to reporters at his Meet-the-People Session at Bedok Reservoir in Aljunied GRC.

2. So what was the duckweed debate really about?

People's Action Party (PAP) MPs criticised Mr Low's analogy.

Ms Rahayu Mahzam, MP for Jurong GRC, said in Parliament on Thursday (Jan 28) that NCMPs are not like duckweed as they can also contribute to parliamentary debates and grassroots work.

MP Edwin Tong (Marine Parade GRC) chimed in.

"Now, suggesting that the NCMPs create duckweeds, I don't think that's true. As the member Rahayu mentioned earlier, you really make what you will of it yourself," he said in Parliament.

By Friday (Jan 29), the analogy has spread as quickly as the fast-growing plant.

MP Lee Bee Wah (Nee Soon GRC), debating the WP motion to fill the NCMP seat Ms Lee turned down, said in her Mandarin speech that Mr Low is trying to let duckweed "drift" into Parliament.

Government Whip Chan Chun Sing assured members that the PAP will never call NCMP "duckweeds" as they are valuable members of the House.

He then added an amendment to the WP motion that it was a "political manoeuvre" by the opposition party to take full advantage of the NCMP scheme even as its chief criticises NCMPs as just "duckweed on the water of the pond".

WP's Daniel Goh later wrote a Facebook post explaining why he will be taking up the post and the party's position.

"Mr Low is right: NCMPs are essentially duckweeds. He is using a Chinese flower metaphor in a very natural way, the significance and nuances of which many of us, Anglophones, don't understand. Very crudely, it means NCMPs are like pretty flowers that sink no roots, floating about and contradicting the values of harmony and community," he wrote.

"Objectively, this is true in the long run, and I am with the WP MPs and the party opposing the NCMP scheme. But for me, personally, at this point in my life, and as I see it, at this point in Singapore's history, the principle of national service trumps the political principle of opposing the NCMP scheme. If my country sees fit that I contribute as duckweed, then it is my honour to be duckweed Goh. It is no insult; it is a privilege."

3. Do duckweeds have roots?

Contrary to what the debate may have you think, some types of duckweeds have roots.

The duckweed tribe of plants are the smallest flowering species known and can be as small as less than 1mm in diameter.

The smallest of the species have no roots, while larger plants types (up to 2cm) have simple roots.

They also have flowers and fruit which are nearly invisible to the naked eye. The green "leaves" that are their most visible structure are known as thallus.

4. A lowly plant?

It's pretty low on the scale of living organisms, but it's more useful than you think.

This tiny aquatic plant has been touted as a nutritious food source. Fast-growing and adaptable, it doubles in size every 16 to 48 hours and even grows in salt water, says biologist John W Cross on his website, The Charms of Duckweed.

It contains more protein than soy beans, and is used as fish feed and chicken feed. Some scientists are exploring ways to feed it to humans.

It is also used to remove contaminants from waste water and researchers use them to study basic plant development and biochemistry.

5. Why compare NCMPs to duckweed though?

The use of "duckweed" to symbolise a person who has no roots is common in Chinese literature.

The Mandarin for duckweed is "fuping", which sounds a lot more poetic. "Fu" means "floating", and one meaning of "ping" is "wandering".

Song and Tang Dynasty poets used it liberally in their verses. For example, the famous Song poet and martyr Wen Tianxiang wrote in his poem, Crossing the Sea of Loneliness, "My life drifts and swirls - patches of duckweed beaten by rain".

6. Who else has used the phrase?

In more recent times, "duckweed" has more commonly been used to describe a person cut off from his cultural roots.

Mr Ho Kah Leong, an artist and former MP, once compared young people with no knowledge of their culture to "rootless duckweed".

Former communist leader Fang Chuang Pi referred to the whole of Singapore as "duckweed".

In an interview with Malaysia's Chinese-language newspaper, Nanyang Siang Pau, in 1997, he said of Singapore: "It is like duckweed, floating at the harbour. When it absorbs fertilisers, it will flourish very quickly. But once it rains and floods set in, it will perish."