Sciencemadness Discussion Board

Why some plants only grow in spring, and not in summer and fall?

RawWork - 2-4-2018 at 16:14

For example why snowdrop appears only in spring, or only on beginning of spring? What prevents it from existing later? Does something kill it? Is some specific parameter or effect responsible?

Could such plants grow forever in a lab aka optimal artificial environment?

happyfooddance - 2-4-2018 at 16:26

Plants, in general, respond (as to germinating, vegetating, and flowering) to 3 significant changes, depending on the species: the light cycle (the amount of time exposed to sunlight, vs. darkness, which is indicative of the season), moisture (also in some cases an indication of season), and temperature (same).

These parameters can be controlled in a lab, and thus can and are used (among other techniques) to both control and learn about the behavior of different plants.

RawWork - 2-4-2018 at 16:33

And fruiting and pollinating? Can they do it every day, forever? So we can prevent them from withering permanently?

happyfooddance - 2-4-2018 at 16:58

Quote: Originally posted by RawWork  
And fruiting and pollinating? Can they do it every day, forever? So we can prevent them from withering permanently?


No, most annuals are diminished by repeated or prolonged fruiting periods. Fruiting and pollinating can be viewed as a sort of "desperation act" on behalf of the plant; they usually put more energy (and nutrients) towards reproducing, at the expense of the health of the mother plant. Basically, the plant puts all of its energy making pollen/fruiting, with the expectation of dying soon afterwards. The plant can be carefully coaxed back into a fruiting mode, and this is done often when one wants to save a particular gene-strain. However, this always results in less vigorous offspring than if one were to breed during the first flowering of a plant grown from seed.

You can keep a clone alive forever, but unfortunately, time is all it takes to make a set of genes weaker. The plant is weaker, and its offspring is, too.

Rhodanide - 5-4-2018 at 09:13

I think that this topic would be better suited for the Biochemistry section :]

happyfooddance - 5-4-2018 at 09:34

Quote: Originally posted by happyfooddance  

The plant can be carefully coaxed back into a fruiting mode, and this is done often when one wants to save a particular gene-strain.


I meant to say "coaxed back into a vegetative mode"

Since it is an old post there was no edit button.

Tsjerk - 5-4-2018 at 12:07

Plants are wonderful in their capabilities, which lead too the periodic behaviour you describe. They are most likely way more complex than we understand now. One species growing and flowering at a certain time a year can be explained by evolution, as it is beneficial for them to spawn at the same time to benefit reproduction.

But plants are so much more soficticated than that
.. I once had a lecture from a professor (I could find his name of you want) who explained the behavior of tobacco plants and his natural enemies and pollinators.

There is evidence, quite compelling even, that plants "know" whether the plants around are direct family or not. They release toxins against caterpillars depending on their own strength, the caterpillar's strength, the time of day and or whether the plants around are family.

If you want to know more about this subject I could find some reviews, or you could Google for the "selfish gene theory". I find this theory absolutely spot on, and I don't know of a single argument against it.

Reboot - 7-4-2018 at 17:53

Many bulb plants (like snowdrops) come from dry mountainous regions. They've evolved to grow fast and bloom in the early spring while water is available (often from snow melt), then go dormant before the dry season comes. It's a more extreme form of the dormancy you see from deciduous trees and other perennial plants; they just go dormant to cope with (what they assume will be) a summer drought rather than to cope with freezing.

There's no inherent reason they couldn't wait until cold weather to go dormant in areas where there's enough rain (or sprinklers) to sustain them through the summer. Given a few hundred years of evolution in our yards, that may very well happen. In fact, it's probably already happened; wild type tulips go dormant in summer, but the highly developed cultivars will stay active until fall.

Melgar - 7-4-2018 at 22:31

So many people saying so many things, and you're pretty much all wrong. There is one main reason, and you all missed it. I assume I'm the only one here who has ever had a beehive. See, during other times of the year, there are a lot more flowers blooming, which means that a bee might not spread the correct pollen to the flower it was meant for. Not to mention, as soon as it gets warm enough for bees to fly around, they're immediately going to make a beeline (pun intended) for whatever the nearest species of blooming flower is. Therefore, what many plants to is they form bulbs. That way they have plenty of energy in the spring to make flowers as soon as it's warm, and there's far less competition from pollinators. The flowers then die off, but the plant is still there in leafy form, storing up energy for a bulb for next spring. It's just that without the blooming flowers, it might be hard to recognize the plant.

Brassica oleracea has a similar strategy, except it stores its energy in enlarged stems and specialized leaves. It only grew in a few niche environments though. It can't deal with being crowded by other plants, but it can grow in salty alkaline soil unlike most plants. Like limestone sea cliffs. Now it grows all over the world though! That's because people figured out that instead of having the plant waste all its stored-up energy on flowering, they could just eat it before it had the chance! Indeed, we probably bred a wider variety of cultivars than any other plant. Cabbage is one, as well as all the various types of cabbage. So are broccoli and cauliflower. So is kale, and collard greens. And brussel sprouts and kohlrabi. All the same species, believe it or not:

https://en.wikipedia.org/wiki/Brassica_oleracea

Tsjerk - 7-4-2018 at 23:13

Bees are far from the only mean of pollination. I even think the percentage of bee pollination is highly exaggerated, as in most researches a bee pollination is extrapolated to the bee being the only mode of pollination.

Laboratory experiments are hard to set up, as e.g. in a greenhouse you also lack other insects and wind, and in natural environments without bees, the reason for the wipe out of the bees probably also wiped out other insects

happyfooddance - 7-4-2018 at 23:18

Quote: Originally posted by Tsjerk  

Laboratory experiments are hard to set up, as e.g. in a greenhouse you also lack other insects and wind, and in natural environments without bees, the reason for the wipe out of the bees probably also wiped out other insects


You have insects in a greenhouse, for sure... And you have fans, simulated wind. If you didn't, the branches wouldn't be strong enough to hold their fruit.

Tsjerk - 7-4-2018 at 23:55

If you keep out bees from a greenhouse, you will most definitely not have a representative group of other insects (maybe you could shoot down bees with a laser, after recognizing them by their wing rithm or something).

Fans that always blow air in the same direction I wouldn't count as a full representator of wind.

Melgar - 8-4-2018 at 01:32

Quote: Originally posted by Tsjerk  
Bees are far from the only mean of pollination. I even think the percentage of bee pollination is highly exaggerated, as in most researches a bee pollination is extrapolated to the bee being the only mode of pollination.

Laboratory experiments are hard to set up, as e.g. in a greenhouse you also lack other insects and wind, and in natural environments without bees, the reason for the wipe out of the bees probably also wiped out other insects

A huge variety of insects eat nectar, not just bees. I mentioned bees because people would probably be familiar with them. Also, I see them a lot in my mom's crocuses when they come up. Flowers exist for one purpose: to attract insects. And hummingbirds too, I suppose. Wind pollinators like corn and grass don't have bright-colored flowers.

Tsjerk: The reason that many flowers bloom first thing in the spring, is that they are more likely to get properly pollinated by nectar-eating insects. This a question that's we've had an answer to for a long time now.

Sulaiman - 8-4-2018 at 03:26

Not all plants require sexual reproduction so the pollination by insects is just one aspect of plant EVOLUTION.

The short answer is evolution,
each genetic mutation dying out or thriving, or just surviving.
To say why a particular plant behaves in a particular way requires a knowledge of its present and past environment and morphology.

Reboot - 8-4-2018 at 05:02

Quote:
The flowers then die off, but the plant is still there in leafy form, storing up energy for a bulb for next spring. It's just that without the blooming flowers, it might be hard to recognize the plant.


It's actually normal for some small bulb plants (like snowdrops and crocuses) to die back by mid summer. After blooming they go through a vegetative phase, where they rebuild their energy reserves, then the leaves die off and the plant will go dormant until next spring.

Pollinator availability certainly might be a factor in the blooming time, but it's heat/water that drove the 'premature' dormancy/dieback.

RawWork - 8-4-2018 at 06:00

I don't know what are genes. But I am learning it. What do you mean offspring will be weaker? Is it something permanent? How to explain that using chemistry or maths? Maybe different geometry?

Is it really true that wind has to be around plant to keep make it's branches and stalk grow strong? Has anybody tested growing them without wind and complaining about weak branches?

Can I grow plants and animals artificially forever? Grasshoppers and frogs are sleeping in winter? Just because of cold?

Tsjerk - 9-4-2018 at 03:32

Quote: Originally posted by Melgar  

Tsjerk: The reason that many flowers bloom first thing in the spring, is that they are more likely to get properly pollinated by nectar-eating insects. This a question that's we've had an answer to for a long time now.


Although I think you are quite correct, I think you should look at it differently. I think the reason for early flowering is because there was a niece in time and space. This niece was found by some genes and therefore there are plants that flower early. The nectar eating genes evolved while finding this niece at the same moment.

I believe it is not correct to say plants flower early because of pollinaters, as the pollinaters wouldn't exist without the flowers. I think it is impossible to point out any other reason for existence of any thread in life other then "because I want to exist". I really like the selfish gene theory,