The world's tiniest waterlily doesn't
grow in water!
by Carlos Magdalena, RBG Kew
Click images to enlarge
was discovered in 1987 by Professor Ebehard Fishcher in Rwanda,
Central Africa, at Mashyzuza near Nyakabuye. This unusual Nymphaea
species is a taxon that ticks all the boxes in my personal
choice plant check list. Lets go point by point.
- Known from only one country and one location, you cant
get more endemic than this. There are some reports that state
that the whole worlds population is around 50 specimens.
Hence it is vital that that we learn how to grow and propagate
this species to preserve it ex situ and if possible to
store seed in a seed banking facility as insurance for the worst
than can happen.
Horticulturally speaking, its difficult
to grow - This species has been growing
for many years at Botanische Gärten Bonn, Germany. It doesnt
seem to form tubers and seeds seem nearly impossible to bring
to maturity. There is a challenge. Good!
Rarity - One
location in the wild and one single botanic garden growing it
should speak for itself.
Oddity - To
me this is a really unusual species. So far, none of my specimens
has developed a spread that surpasses 10cm (4). I guess
that they will get larger than that but I cant recall any
Nymphaea species that flowers at such a tiny spread.
Despite being a tropical day bloomer placed
amongst the Nymphaea subgenus Brachyceras, the
leaves are typical of a Nymphaea subgenus Nymphaea.
There are no markings on the undersides; they are almost perfectly
round with a totally smooth margin, no teeth at all; petioles
are shorter than the leaf blades. Sepals (which are a bit hairy
) seem to be as large as flower petals. The plant doesnt
seem to form tubers; seeds are quite large for a Nymphaea
subgenus Brachyceras and dark black in colour. Surely,
these abnormalities must come as an adaptation to:
An unusual habitat.
It doesnt grow in a lake; it doesnt grow in a river;
it doesnt grow in a marsh or in a bog or small pond. Where
does it grow? This species grows in a thermal hot spring. It
is the only place where it can be found.
- If you agree with all the above, you surely agree that this
species is of high scientific interest.
- Well, I really do think this little plant can change the face
of tropical hybrid production. So many unusual traits could be
added into the hybrids gene pool and this cant be
bad at all. The only down side I can see is the very low petal
count, but if some of the hybrids are not sterile, which seems
quite likely, this can be surely fixed at a later day. Yes, you
just guessed it
I plan to use it! So far the priority
is to reproduce the true species, a must given the conservation
importance, but once this is done
why not? Watch this
Raising a No-Water-Lily????
Seeds of Nymphaea thermarum germinate
very easily. However, if grown like any other Nymphaea
they simply dont grow. I was sent seeds from Bonn Botanic
Gardens once and none of the many seedlings got anywhere. This
was very frustrating. I tried to gather as much info as I could
(not much!). Not being able to communicate with anybody that
has seen it in the wild was a constraint. Then I found this.
Eine sehr seltene und endemische
thermarum wurde erst 1987 von Prof. Dr. Eberhard Fischer entdeckt
und konnte bisher nur in der heissen Quelle (40°) Mashyuza
bei Nyakabuye nachgewiesen werden. In den Abläufen dieser
Thermalquellen wächst Nymphaea thermarum bei ca.
24 bis 26° C Wassertemperatur.
Believe it or not, this is great. Oh yes,
a small detail. This is great if you translate it from the German.
One of our Kew Diploma students, Felix Merklinger; did a translation
from this text for us now to enjoy
A very rare and beautiful species.
thermarum was only discovered in 1987 by Prof Dr Eberhard
Fischer and is so far only known from the hot springs (40C [104F])
Mashyuza near Nyakabuye. In the overflows of the springs (I
guess he means where the water drains from the hot springs in
little channels), Nymphaea thermarum grows at approximately
24-26C [75-79F] water temperature."
This gave me a few clues:
It then doesnt need to be grown in piping
The quotation provides a temperature where it naturally grows.
Then I thought
which possible parameters
can affect the seedling growth?
Temperature - seems specified at 24-26C (75-79F),
but it may worth trying different ones such as 30-32C (86-90F)
Nutrients/compost - Loam? Loam + food? Peat/sand?
In the case of using the first two, you can almost predict for
sure that you will have hard water, especially in a small tank,
and high electric conductivity.
pH, hardiness, electrical conductivity - those
usually tie up together: hard-alkaline-high electrical conductivity
or soft-acidic-neutral to low conductivity.
And then the Achilles heel of the submerged
I can control all of those at Kew. All but
Then I thought about asking for more seed
and running a trial. Two different temperatures: 23/24C (73/75F)
and 30/32C (86/90F). Two different water qualities: hard and
soft. Two different media: a rich loam and a peat/sand for the
They didnt like it, especially the warmer
conditions and, for the worst, the warm low nutrients. So there
was a conclusion here. It doesnt like it that warm, at
least as seedlings, and acidic soft water does not do much for
them either. So it seems like it may need CO2 but I dont
have a CO2 injector. How could I overcome this? I thought
well, if oxygen dissolves more at the surface of the water (the
reason behind of fish constantly surfacing in hot/anoxic conditions
CO2 may do the same. Then I remembered the staff in Bonn said
that it likes it shallow. Then I re-read the German paragraph
and tried to imagine the conditions
and the overflows
and the little channels and I thought - eureka!!!! What about
keeping them so shallow that they actually touch the air surface?
I re-sowed the seeds, some in a pot in water
1mm (.04) deep, others in totally soaked and undrained
damp loam. For the ones in damp loam, I suspected that if they
dried on the surface for a second they would go crispy, so I
placed them inside the misting unit so they stayed in 100% humidity.
It worked! The ones that were 1mm (.04)
deep started to grow leaves that were submerged in shape but
touching the surface. The ones that were in the loam did the
same, but as they were out of the water they were smaller but
thicker. Amazingly for those in damp loam, the first filiform
leaf grew erect and totally out of the water, just like a blade
of grass does. The hastates and following leaves became something
like floating in mud leaves.
Then I decided to try a third thing -- to
transplant a few of the seedlings from both locations into damp
loam in a pot that was placed in a water-retaining container
that was filled with water to the very same level as the loam
in the pot. This was then placed on a heating mat at 24C (75F),
in a very bright light location, brighter than the two previous
experiments. Every single plant grew even better as you can see
in the pictures with this article.
Remarkably, I could observe that the meristem
of this species is sunken in the mud, probably an adaptation
to the no water/shallow conditions where it lives, to prevent
dehydration in the very early stages of leaf development.
This is an example of how re-creating wild conditions
sometimes is absolutely essential. Imagination sometimes is crucial
and information about the biological challenges and conditions
in situ critical.
Nymphaea thermarum recipe:
Find a small container that can hold water. Look for a pot
that can be fitted into it, smaller in width but jut a little
bit lower than the container.
Fill the container with water. Fill the pot with fine soil
to the very top. Place the pot inside the container. The water
level of container and pot should be exactly the same (or that's
what we should aim for!). Once the soil is totally damp and settled,
sow a few seeds by sprinkling them onto the surface. Remember
the water level is crucial! It can go down for 1-2mm (.04-.08)
or up for 1/2mm (.02), but air exposure is a must! If you
have a tiny watering can you can check and refill the larger
the water tank every day, slowly. Keep at 22C-26C (72-79F)
Im not sure if more or less heat will affect them, but
that has worked so far!! You can have water heating in a larger
container and then place it in the smaller one, or place the
small container on a heating mat or bench at 24-26C (75-79F).
I have done both and both work!
Amazingly the first filiform leaf will emerge, get out of
the water and it will be a happy guy. I never thought a Nymphaea
seedling would cope with that! Then it will get CO2 from the
air while being totally hydrated as the base is in water. Then
it will grow second and third leaves
those are round and
they will be out of the water or have the underside touching
the soggy loam and the upper touching the air. They will sort
themselves out if you are accurate with the water level.
Expose them to the sunniest of your locations (now that we
head for winter in the UK, maybe additional light will be required
A few weeks or months later (not long!!!), you should have
them blooming! Prick them out into individual pots when they
are large enough to handle (5 leaves of 1/2cm [.2] wide).
Did I just mention the word imagination? Can
I then use it and even get carried away by it? Here I go
despite their totally
aquatic range at present, Nymphaeales evolved on land
and then made it into the water. The terrestrial members became
extinct and the aquatic ones originated the waterlilies.
is N. themarum a terrestrial
waterlily making its way into the water from a terrestrial ancestor
and hence a very primitive member of the family, or somebody
getting out of the water, making it one of the most adventurous
species that is making the terrestrial leap once
again. Given its difficulties when growing underwater, Im
inclined to think that it is getting in the water, but was a
Nymphaea the genus that first made it into the water?
I doubt it
but for sure we can use our imagination to
figure this out (well yes, and DNA studies, analysis of fossil
basal Angiosperms, micromorphology applied to evolutionary science,
and many other amazing research techniques may help, indeed!!!).
Could this species
enable us to obtain hybrids that grow out of the water and are
compact enough to grow in a bowl of wet loam? In what colour
would you like your hanging basket with a semi-epiphytic waterlily
next summer? And when we thought that we have seen them all ...
Special thanks to Botanische Gärten Bonn
for providing the seeds to RBG Kew.
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