Wow Linda! What a great reply! Thanks. :-)
You're sure welcome!
I'm enjoying this discussion myself. I like exercising my brain and thinking about stuff like this, and the questions raised and ideas presented in this thread sure are making me think.
I love your discussion of true annuals. And your tip about restricting my research to places that drastically seasonally seems like a good idea... but wouldn't that encourage plants to not be true aquatics? Having a emersed form? Or am I missing something?
Yes, you are right ~ that would surely encourage plants to not be true aquatics. That's probably exactly why most of our aquatic plants aren't true aquatic-only plants. But it's a definite possibility (a probability actually) that at least a few plants wouldn't have been able to make the transition to emersed growth. Those plants had a "choice" ~ use another mechanism to keep the species going (such as seeds) or become extinct. Some of them adapted and some didn't.
It's amazing the number of different ways plants have evolved to "hang in there". There are plants that never stop growing no matter what time of year, plants that go dormant in winter by dying back to the ground and re-emerging from their rootballs (or corms or tubers or bulbs) in spring, plants that go dormant but just lose their leaves then sprout them anew in spring and some plants that might go dormant but don't even lose a bud. There are plants that propagate themselves by offsets of bulbs, runners sent out from the mother plant, rooting from a branch that touches the ground, sprouting from a piece of root (not a bulb, corm, etc. ~ just a piece of root severed from the mother plant) and even some that will sprout roots from a small piece of leaf! Incredible.
And seeds! The different mechanisms that seeds use to "know" when to sprout is just amazing. Some need a certain temperature, some need a certain day length (yes, some seeds can tell time!
), some need a long wet monsoon. Some will lay in the ground for years until they are uncovered (as by plowing) and sun hits them for just a split second, and that's all that's needed for them to sprout, even if the plowing immediately covers them right back up. That's it ~ just a split second of light! Amazing.
And did you know there are seeds for certain plants that must
hang around in their environment for years before sprouting to allow the weathering of their tough seed coat? Then, when the seed coat's thin enough and conditions are right for them, they sprout. And it's individual to the seed even ~ some weather faster than others of the same species. This appears to be a mechanism developed to allow the species to survive despite frequent drought years ~ the sprouting of the seeds would be staggered, so the ones that sprouted in year one of an extended drought wouldn't make it, while year four seeds would since the rains would come back by then. Lotus is one, the big pond lotus ~ Nelumbo spp.
And there are others and they're not as uncommon as you think ~ some hard-shelled nuts are that way, though most nuts' shells probably developed their hardness more as a safeguard against getting eaten too easily by wildlife.
And think about that for a bit ~ that nuts developed such a hard shell to keep from being eaten. Imagine ~ if there were no such thing as squirrels, it'd probably be a helluva lot easier for us to eat walnuts.
Here's a neat story about the tenacity of seeds~ A few years ago, I tilled an area out here that hadn't been tilled in twenty years. There were NO unicorn plants (Proboscidea louisianica
) growing within two hundred feet of that area for that entire twenty years, and only a couple-three plants growing anywhere on the ranch during that time. Yet, once that area was tilled, the unicorns popped right up en masse. The seeds are too heavy for them to have been blown or washed into this spot, and there isn't a luscious "fruit" for the birds to eat and therefore spread them (they're spread by those "talons" on the seed pod that grab ahold of an animal as it goes by). Those seeds laid there in that ground until I tilled it, watered it and fed it ~ twenty years
after they formed. Incredible.
Can you tell I have a thing for seeds?
Plants of all types, really. And Mother Nature in general. I tend to go on and on and ON when talking about them. Sorry.
Either way, you post is why I love this place... ask a good enough question, and some well informed people are likely to show up! Once again I'm humbled by my lack of knowledge, but am happy to post at a place where there is such a deep well of knowledge to tap. Thanks!
Isn't that cool about this forum? I spilled coffee on my laptop keyboard and the enter key wouldn't work anymore. I thought I was in for a LARGE repair bill or a new computer since I'm pretty much a computer dummy. I posted about it just to see if there was any other thing I could do than lug around an external keyboard or pay through the nose and bingo! Someone linked me to a neat little program where I can "re-key" unused keys on my keyboard to do something else. I got my enter key back and it cost about an hour instead of hundreds of bucks. I'm a happy girl!
Yep, this place is great