Aquatic plants Gardening Sowing Seeds Water gardens

Mystery Seedling Results in Floating Surprise

Many years ago, when I was experimenting with container water gardens, I came across some mysterious seedlings growing in the bottom of a half-whiskey barrel.

This was in early March. I had brought the barrel inside my greenhouse for the winter to overwinter a small tropical water lily. The main experiment had not been a success. The water lily had weakened under the short days and cool temperatures of the greenhouse, so I finally had to move the plant to a warmer spot under intense artificial light and that meant into a much smaller container. The barrel was just too big.

Underwater Seedlings?

Still, I simply left the container there, nearly full of clear water, without giving it any special attention. And that’s when I noticed something growing at the bottom. Yes, under water! A few seedlings had appeared and were growing there, seedlings with simple, lanceolate cotyledons, rather thick… I would have said they were something like little amaryllis (Hippeastrum) leaves. I had no idea what they could be, but they were growing quite vigorously, and I was more than willing to give them a chance. Besides I had never seen seedlings sprout underwater before, so I was intrigued.

It’s unfortunate that I didn’t think to take any photos, but—what can I say? I didn’t! The next leaves that came in were rounder, but still unrecognizable to me. Shiny, green, with a short, thick petiole. What could they be?

Relics of the Previous Summer

Water hyacinth with lavender flowers in bloom.
Water hyacinth (Pontederia crassipes). Photo: olovedog1, depositphotos

I got the answer one morning in April, when the little seedlings suddenly turned up happily floating at the surface of the water. Why, they were baby water hyacinths (Pontederia crassipes, formerly Eichhornia crassipes), of course! It would appear that water hyacinth seeds germinate underwater, root in the soil there, then rise to the top to take up their usual floating lifestyle when they’re good and ready.

Who knew?

I had been growing water hyacinths in the half barrel the summer before. Clearly, they had produced seed without my noticing.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

9 comments on “Mystery Seedling Results in Floating Surprise

  1. The most invasion water plant going, a real threat to rivers and potable water reserves, burn it.

  2. Oh, I should have guessed! This is one of the worst aggressively invasive exotic species in California now, although not many are aware of it, because it is an aquatic weed.

  3. Diane Duford

    Nature at its best :).

  4. This one made me shudder, being from Florida, where it is a bad invasive species. What we are seeing where we introduce plants into new areas where they are not subjected to predation from their co-evolved “population check” animals, is increased reproduction and rapid adaptation to their new surroundings.

    These are beautiful plants…but they too want to rule the world! As growers and lovers of all things different and exotic (yes, I am a plantaholic as much as anyone else) we need to be very observant…and extremely thoughtful of what we do with our unwanted extra plants. I was very surprised to see that there is concern about this plant in Ontario, as I thought it only liked warm sub-tropical waters.

    Tossing unwanted pond plants into wet areas is probably unadvisable. Make sure they are “crispy dead” when finished with them, and be aware that it is possible to inadvertently spread seeds or parts of roots that may grow, leaving a permanent legacy in your community.

    These are living things that can reproduce in uncontrolled ways that can challenge both humans and local animals for space and food supply.

    There are often unanticipated impacts ecologically that can create a domino-effect-like trophic cascade of unexpected results. Sometimes these changes take a long time to occur as the plant adapts to its new surroundings, and when it “figures out” what will work there is a population explosion…this can happen in a few years or take more than a century and is called “the lag effect”. This is how plants can fool us into thinking they are harmless…because we tend not to choose prevention or pay attention until invasions are well advanced…and then it becomes a very expensive problem to solve…if that is even possible.

    • Around northern Indiana we have that issue with Purple Loosestrife (Lythrum salicaria).
      Suburbanites think they’re so pretty (yeah, they are), but they’re overstaying their welcome.
      They’re not native and they’re getting to be everywhere.

      My MIL has a small slough she keeps natural on her farmland. Darn stuff is taking over. Natives are pushed aside. When the wetland naturally dried she mowed and let the stuff dry in place. The she burned it over, raked, reburned and plowed everything under.

      That cleared things for about 3 years. Now, it’s all back to square one. Looks like another burn session on the horizon. She doesn’t want to use chemicals and physically digging out the loosestrife is beyond her. The stuff’s vicious.

      The slough is hardly natural any longer with all the stuff being done to control the invaders because native plants and animals are just as vulnerable to this process.

      Some neighbors (not farmers) complained because the “pretty flowers” were destroyed and they didn’t like the burn (welcome to the country). It was a controlled burn with a water tanker on standby.

      MIL wants to tear her hair out.

  5. Gotta love these little surprises!

  6. Cool! I didn’t know P. crassipes did that! I wonder if there are other plants that exhibit this interesting lifestyle? i.e., seed and sprout underwater as an attached plant, and then spontaneously turn into a floating one?

  7. Granny Pat

    I’ve heard that water hyacinth are pretty aggressive so would that mean that you couldn’t grow anything except them in that container? No mixed plantings for variety and height possible then? Did you end up keeping the WH? Was the experiment worth it? Would WH make a good houseplant? If left outdoors (no greenhouse, NB temps) would it come back next year? Pretty flowers anyway.

  8. Wow, that is veery interesting. Like you said, who knew.

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