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This tiny waterlily brings new potential for
small hybrids -


 Lusty Li'l
Nymphaea minuta

by Rich Sacher
New Orleans, Louisiana USA
Click images to enlarge

A number of years ago, a new dwarf tropical lily was discovered in Madagascar. It is a very small tropical lily with off-white to light pink flowers; it can bloom in much shadier conditions than most waterlilies and sets seed prolifically. It has been making its way around the world and into the hands of hybridists, who are working with N. minuta in hopes of creating a series of attractive dwarf waterlilies.

Those of us in this hobby and industry have been saying for years that we need to develop a line of truly dwarf tropical lilies. Since many tropical lilies have a spread of anywhere from five to ten feet (one and a half to three meters), then I suppose a dwarf lily should be noticeably smaller than that, perhaps with a spread of no more than two feet (0.6 meters).

A dwarf tropical lily would be perfect for those whose water gardens are in containers or small tubs. In a pond of three to four feet in diameter (one to 1.2 meters), several dwarf lilies could be grown in place of one larger one, allowing for a collection of varieties with different flower colors and leaf patterns.

Some of the qualities which would be desirable in a dwarf tropical lily include compact habit and flowers that open early and close late. Large flowers with lots of petals, in a variety of colors, would be on everyone's wish list. Nice markings on variegated leaves would add to their appeal. While we are daydreaming, make these new dwarfs easy to grow, too.


N. colorata 
 Right now, the closest thing we have to a dwarf tropical lily is N. colorata. With its compact form, smaller leaves and blue flower with purple stamens, it has often been our only tropical for really small water gardens. Colorata's growth can be restricted by growing it in a 4 to 5 inch (10 to 13 centimeter) pot, and by reducing the fertilizer schedule. This "dwarfs" the lily by cultural means, but this variety remains a small lily, not a true miniature. Given enough soil and fertilizer, colorata usually attains a summer spread of three feet (one meter) or more.  

N. minuta, however, is a true miniature waterlily. It is something of an oddity, because it has been described as cleistogamous … that is, the flower can pollinate itself even if the flower remains closed under water. In addition, a first day emergent flower often opens with pollen already present; thus, it sets seeds abundantly by self-pollination. When grown in shade and cooler temperatures, minuta reverts to a submerged form, producing submerged leaves and flowers. Its flower is small, up to one and a half inches (four centimeters) in diameter, and often has only 10 to12 petals. Not very showy at all.

Some hybridizers have produced crosses with minuta that resulted in variegated leaves and blue flowers. This initial work is promising, showing that minuta may be a prime candidate for producing new dwarf waterlilies. So far, these hybrids exhibit flowers which are quite small, with few petals; and the color needs improvement. In addition, there are some obstacles to overcome in working with minuta.  

1) Since the flowers of minuta can self-pollinate before they open, the flowers should have their stamens removed before that happens. You have to decide how close the flower is to its first day opening, and remove its stamens before then. If you wait until the normal opening of the first day flower, your introduced pollen will certainly be accompanied by pollen from minuta itself, resulting in a mixture of self-pollinated and cross-pollinated seeds. Microscopic examination of stamens from minuta flowers that were just beginning to open confirmed for me that viable pollen is routinely present before the flower opens for the first time

2) Since minuta's flowers are less than two inches (five centimeters) in diameter and have relatively few petals, continued hybridization will be needed to increase the flower size, color and petal count, while retaining its dwarf characteristics.

3) Minuta needs to be used both as a seed parent and as a pollen donor, in multiple trials, to see where the best results are obtained.

4) It will be a challenge to maintain a dwarf habit in these new hybrids, while producing a showy plant that grows vigorously enough to be successful in the hands of an average water gardener.

Last November I was fortunate enough to be given a minuta by David Curtright of California. It was a healthy plant with tiny flower buds and leaves only an inch (2.5 centimeters) across. I began hybridizing with it right away using a pink variegated tropical lily for the pollen donor. The first crop of seeds was produced 30 days after pollination. They were planted immediately, and within two weeks, some seeds were beginning to germinate. The initial leaves on these seedlings show a variety of colors: some are plain green, while others are variegated, indicating that at least some of these seeds are a result of cross-pollination.  


 N. minuta in November 2007
with a dime on the leaf 


Thermoplanter
 This minuta was grown in my greenhouse pond where the night time air temperature is only 60° F (15° C) … and by November the plant had stopped producing flower buds. This may have been in response to the shorter day lengths, or the low night time temperature … or both.
David had also sent a minuta to Kit Knotts in Florida. When we visited Kit in November, she said she needed a good home for her minuta. It was making seedlings all over the place, and competing with her Victoria seedlings. I volunteered to adopt this second minuta.


Agrosun lamp
When I returned home I planted both plants in a 12 inch (30 centimeter) diameter Thermoplanter, which warms the soil to 80° F (27° C) … and I installed a 400 watt Agrosun halide/sodium lamp about 12 inches (30 centimeters) above the potted plants. Within three weeks, the minuta which had stopped blooming was once again producing flowers.  

Because the lamp is left on all day and night, it is not possible for me to say what the "normal" behavior of minuta is. However, its leaves are now four times bigger than when I received the plants; they have developed a violet color to the underside of the leaf, and even some violet shading on the leaf surfaces.
  This may be a result of uninterrupted artificial light, but until I have grown the plants outdoors through an entire year, I will not know how minuta behaves during a normal summer season.

 

What is obvious already is that minuta remains a dwarf plant, even when grown in warm soil with high fertility and 24 hour light. It sets seeds easily (maybe TOO easily!) and has already proven to be a successful seed parent in cross-pollination with other hybrid lilies. Even under less than ideal conditions, minuta has proven to be a steady bloomer, yielding an uninterrupted succession of flowers.

Will minuta be the parent we have been looking for in our quest for dwarf tropical lilies? We don't ask for much … just lots of flowers … with lots of petals … in many different colors … and nicely variegated leaves … on a small plant that is easy to grow. Wouldn't it be great if all these big dreams come true because of an ordinary little lily called minuta?


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