One of the few people to grow both Nymphaea minuta and
the Australian N. nouchali -


Read about
Carlos Magdalena

Carlos Magdalena,
Royal Botanic Gardens, Kew, discusses
the Miniature Tropicals,
their status, their cultivation, and his method of sowing seeds

Click images to enlarge

 
 

 

Australian
Nymphaea nouchali

After managing to germinate and grow this plant, collected in Australia, to maturity, I have two different theories:

- Either this is a different species, probably new, and not N. nouchali

- Or nearly all the plants in cultivation under N. nouchali are misnamed plants and this is the true N. nouchali (maybe a different Australian subspecies?)

From a horticulturist's point of view, there is little I can do to resolve this enigma, apart of supplying plant material for DNA testing or for further botanical research. Obviously, tracking back to the herbarium type specimen for N. nouchali would be more than desirable as this will be the ultimate proof of what type of plant would keep the name N. nouchali.

For me, N. nouchali has never been a "clear" species. Looking at pictures of what the growers have as N. nouchali it is clear that either the plant is highly variable (which I doubt) or that this name is being used wrong. Despite my not being a botanist, I always feel confident telling apart species of Nymphaea that I have previously grown, but I must admit that I never feel like this when the name N. nouchali pops out.

Nymphaea nouchali and Nymphaea stellata seem to be used in the trade as a substitute for the more precise terms Nymphaea sp. or Nymphaea hybrid of unknown origin. Luckily, the latter name (Nymphaea stellata) appears to be not a valid name any longer and therefore any plant that is named N. stellata is wrongly named since this name does not exist. However; N. nouchali is a valid name, but there seems to be a problem here: there is a true N. nouchali somewhere, but there are several plants in cultivation that probably do not fit the original description and the type specimen. I would refer to them as "folkloric" N. nouchali.

I guess that the "folkloric" nouchali have arisen for different reasons. One can be misnamed plants in cultivation by growers; another can be misuse of the name by botanists (N. nouchali seems to be cited in many African floras, where this species just occurs in Australasia; and finally, the proliferation of introduced hybrids into wild areas of Asia that vaguely match the description of N. nouchali and somehow end up being classified as nouchali.

What seems clear to me is that this name is commonly misused so further research needs to be done to shed some light in the true identity of this species. I hope most of the Nymphaea growers and botanists will agree with me on this point. It may happen that this research has been done already. If this is the case, I hope that whatever has been the latest decision/conclusion it gets widely divulgated to avoid further confusion. I hope that the publication of this article will help to shed light on the true characteristics of what could be a taxonomically accurate N. nouchali.

Nymphaea is a genus that can be very confusing. Currently, the accepted names cover about 40 species. Despite this, in the past up to 370 botanical names have been described. Most of them are currently invalid names but a fraction of those still survive: for example N. rubra, N. spontanea, N. zenkeri. While some of these names may make sense to some, we must emphasize that they are not scientifically valid and therefore they should not be used as such. If they are used at all then we should refer to them as N. 'Spontanea' or N. lotus 'Spontanea', but not before someone takes the trouble to officially name them as cultivars or hybrids, as there are rules to follow if this is the case too.

 

Cultivation of
Australian N. nouchali
 

Nymphaea minuta

Suddenly one day when working with the aquatics at Kew this tiny pink flower popped out. I thought … what?! I was not aware that there was a Nymphaea so small?!? I pulled out the label and I could read N. minuta and thought, indeed, so minute!

Looking at the records, I could not find such a name in the database or in the official listings of plant names or cultivars. It wasn't accessioned yet either. I thought, well, the Nymphaea growers are going to love this one!

I thought about telling everyone about my backyard discovery (in this case back pond) but after enquiring at Kew's Records Office I learnt that it was totally restricted. I thought that it would not be polite to say, "I got this!" and "but I can't give it away so you can't have it!" As well, at this time I had no idea where it came from or how rare it was, so I decided to give it a while before I could contact the donor and find out if I could release this to everyone interested.

By the time I managed to do so, I had realized a few things:

- It has a weedy habit. N. minuta seedlings were growing all over the tanks.
- It is a species and not a hybrid, as all the seedlings look the same when flowering.
- It can flower in dark cool conditions.
- It flowers even without floating leaves.

After a few weeks I did another Internet search and more info popped out. I learned that it was a new species not described yet and that it was endemic to a single pond in Madagascar (wonder why as it is so weedy!). I even came across an article in which someone was claiming that this was almost impossible to grow and that several botanists failed to grow it. I just wondered if we were talking about the same plant or if those botanists tried to grow it on a herbarium shelf rather that in water, as my problem was to contain this species rather than keep it alive!

Soon after I was glad to see that this plant was starting to be widely distributed. Eventually it got named and described by K.C. Landon et al, which was very good news. I don't like to accession species that don't have official names!

In my experience this plant is one of the easiest tropical Nymphaeas either from seed or as an adult plant. It takes heat, cool, sun, shade and is reluctant (in my experience) to go dormant and form a tuber, even if grown in a tiny pot and without feeding it at all! (It will not flower though.)

It is not a heavy bloomer, perhaps because every single flower leads to a fruit, but flowering improves greatly with a bigger pot and plenty of food. It is quite varied in size, leaf colour and habit (submerged or floating). A change in the conditions will always lead to the plant shifting to a different form/growth habit, so it seems to be very adaptable.

I would not want to finish this article without a warning! If you are a grower in the tropics … please be extremely careful with this one! We don't want to have another invasive such as water hyacinth or N. mexicana. Don't believe that you can pull out every fruit as it will always manage to hide one (flowers don't need to open on the surface to develop a fruit and this species is extremely fast to pull the self-pollinated flowers down to the very bottom).

In some conditions it is not so weedy. After growing it in one of our public glasshouse's pond, not a single seedling was found! This maybe was due to the many fish and tadpoles living in there, and I can't think of any other reason. Having said that, don't experiment! Given "wild" conditions, it will stay there and, as with many other weeds, it will be there to stay. This warning may be a bit too late …???? Has anybody seen it growing in the wild (other than Madagascar, of course)?

 

Thanks to Dr. Barre Hellquist, who very kindly obtained and distributed this species, two different batches of seed reached the Royal Botanic Gardens, Kew, during 2007 and 2008:

- A batch of seeds (dried) collected at Queensland's Cairns Airport, where this species has colonized the airport's drainage ditches

- A batch of seeds (dried) from a population in Wonga Beach, Queensland

Unfortunately, I did not manage to grow any seedlings from the population at the airport, but I was lucky enough to be able to grow to maturity plants from the seed collected in Wonga Beach.

Seeds were germinated at 31C (88F) but the seedlings did not thrive under the conditions I was providing. The seedlings were not increasing in size and the few submerged leaves that grew were very small and dark brown in colour. Aware of the mainly coastal distribution of the species, I set up a tank at the same temperature as the first trial but I added 1/6 sea water. This trick did wonders and soon some seedlings started to grow properly. This time, seedlings bore emerald green leaves that gradually increased in size, eventually leading to adult flowering plants that have produced further seeds.

It seems clear that this species needs brackish water or at least alkaline conditions to be grown from seed (the water previously used was very soft with a neutral to acidic pH). However, it may be that once it has reached adult stage it may survive other conditions and therefore can be used for pond culture. I have not tried this yet as I wanted to secure a good amount of seed first and establish more plants in the conditions they seem to like at present. At the moment, I'm trying to germinate seeds that were produced in the last few weeks and then I will try to grow a mature plant without any salt water being added.

A plant of this species can be grown to maturity and set seed in a tank as small as 35cm long by 20cm deep by 20cm high (14" by 8" by 8"). It can be grown quite shallow (15cm [6"]) in small pots, with no filtration in the tank and temperatures ranging from 28C to 32C (82F to 90F). One of the biggest problems I face is that the snails (Limnaea) seem to love this plant and seedlings are their favourite choice. Perhaps this is due to the high concentration of salts in the plant and water, as the snails seem to move from the soft water into the brackish tank, probably looking for the necessary ingredients to build up a healthy shell.

Seedlings are quite slow to develop and it takes about two or three months for them to start producing floating leaves (Anecphya seedlings can be flowering in the same amount of time at the same temperature and light levels …). However they start flowering once they have developed six or seven floating leaves. Despite germinating many seedlings, I just have two plants at present, as many were lost to the snails (which I need to remove from the tank almost on a daily basis). 

 

Sowing Seeds

The seeds are sown dry. Dry seeds tend to float and to avoid losing seeds (and eventually, to avoid the collection getting mixed as free-roaming seeds colonize other pots …) I first fill a pot with fine loam almost to the rim, but leave at least a 1/2cm (.2") gap as the loam tends to expand when wet. (Otherwise you can end up with a pan that looks more like a muffin!) After pressing the compost down a bit (to avoid the compost opening a gap between the loam and the pot wall…) I sink it into the water to prevent bubbles popping out disturbing the seeds later. Once the pot is totally wet and has stopped bubbling (ideally it should be left overnight, but ten minutes is much better than nothing!) I get the pot out of the water, leave the water to drain by itself for a few seconds and flatten out the surface again if this is necessary. Then I sprinkle the dried seeds randomly onto the surface. As the surface is wet they stick to it. If they are large (such as Anecphya) I push them with my fingers until they are half buried but still on the surface (this helps them to get stuck to the loam). After doing this a very fine layer of sand can be sprinkled on the top. For seeds as small as Aussie nouchali, this layer should not be thicker than 2 or three grains of sand! (well …you know what I mean …) as they are really small. Once all of this is done, as the seeds were previously dried (therefore they should float) I don't sink the pots back in the tank. There are two things that can be done:

- Either place the pot in a tray that has 3 or 4 cm (1.2 or 1.6") of water. Water will flood the loam by capillarity and the surface of the pot will be damp, enabling the seeds to imbibe water during the next 24 hours, making them "sinkable" objects.

- Or place the pot in a tray that has deeper water. The depth should be a couple of millimetres higher than the compost line in the pot, but at least a couple of millimetres shallower than the rim of the pot. This will make some seeds float but they will not be allowed to leave the pot area and sooner or later they will sink.

It may sound a bit "too much" but for me, this is much faster than wetting the seeds in a plastic bag and then picking them one by one and placing them into the pot. In the case of Aussie nouchali picking the seeds one by one is almost impossible due to their size! 

 
Another problem I found is that some seedlings tend to develop a floating habit (after they have grown the first hastate leaf) and they keep "flying" away from the pot. Often they are lost or tend to get in dark places where they can't develop further. If I plant them again, sooner or later I find them floating. Seeds are really small (perhaps the smallest seeds in the genus Nymphaea) and globose (spherical?) and therefore the seedlings are minute too, to an extent that the filiform leaf is almost invisible (I often notice the seedling once it has grown a hastate). I have the feeling that snails destroy many seedlings just by "walking" into the seed pan and knocking the seedlings out, even if they don't bite them. It is quite interesting that the best seedlings developed very close to the label, especially in the 1mm (.04") gap between the label and the pot. I think this position makes it difficult for the snails to get them as they have to carry a shell, so they move on to munch somewhere else.   

The Miniature Tropicals
Introduction & Index
Articles by
Ivan Nozaic | Andre Leu | Carlos Magdalena | Walter Pagels

John Wiersema | Barre Hellquist | Nan Bailey | David Curtright
New Miniature Hybrids by
Carlos Magdalena | Rich Sacher

WGI ONLINE Journal Table of Contents