Factors affecting cold hardiness

[Zeeth]

There are certain factors I know of, such as proper fertilization, but what are some others? Are palms better able to take cold if given more CO2 rich air? What exactly makes palms like Butia and Jubaea so hardy, while coconuts fry at the first sign of frost. Your opinions?

Keith

[SunnyFl]

There are certain factors I know of, such as proper fertilization, but what are some others? Are palms better able to take cold if given more CO2 rich air? What exactly makes palms like Butia and Jubaea so hardy, while coconuts fry at the first sign of frost. Your opinions?

Keith

Probably the biggest factor is the conditions in their native habitat. The coconut in its native habitat(s) didn't have to deal with frost. So it didn't adapt to it. Butias, however, come from higher altitudes - regions where they experience more cold, so they had to adapt or they wouldn't survive. There are exceptions, so there's probably more to it than that.

[Zeeth]

There are certain factors I know of, such as proper fertilization, but what are some others? Are palms better able to take cold if given more CO2 rich air? What exactly makes palms like Butia and Jubaea so hardy, while coconuts fry at the first sign of frost. Your opinions?

Keith

Probably the biggest factor is the conditions in their native habitat. The coconut in its native habitat(s) didn't have to deal with frost. So it didn't adapt to it. Butias, however, come from higher altitudes - regions where they experience more cold, so they had to adapt or they wouldn't survive. There are exceptions, so there's probably more to it than that.

Yes, the palm must evolve over time to cope with the cold or die. But, what makes it hardier? Yes, it is from somewhere where it experiences cold, but what biological factors make it able to cope with the cold?

[palmsOrl]

I will take a stab in the dark to answer that Zeeth. Pure water freezes at 32 F, however, the freezing point of water can be lowered by the presence of various types of organic and inorganic molecules. The liquid present within the tissues of palm leaves (and other parts) contains a multitude of these molecules. Therefore, I believe a palm species' particular biological tolerance for freezing conditions depends (at least partly) on the exact types and concentrations of these substances within its tissues. I would be very interested if somebody could shed more light on the processes that determine the freeze tolerance of individual species.

-Michael

[mjff]

A lot of it also has to do with drought tolerance. If you look at the list of the cold hardiest palms most come from desert areas or areas prone to lengthy droughts. The same factors that help a plant survive drought also help it survive cold. Makes it easy for me to pick palms, since my area is both drought prone and experiences some pretty severe cold.

[sarasota alex]

I believe it's all about the ability to hibernate. Instead of comparing a Butia and a Coconut, let's compare an alligator and a human. Humans body is basically as tropical as they get. It would be hard for a person to survive the latest spell of cold weather down here in Florida outside and naked. That's because we are unable to stop any of our vital processes for a period of time. We can't hibernate. Neither can a coconut. An alligator on the other hand, would perfectly fine for weeks in near freezing water, where a man would die of hypothermia within hours. When it gets cold alligators just start shutting down one system of organs after another, starting with the digestive system and ending with a complete shutdown. I think the same goes for cold-tolerant palms.

Martin I think you make a very good point about the drought tolerance, it's also a form of hibernation. A tree that hibernates well under one condition, can probably do so under another.

[Zeeth]

I believe it's all about the ability to hibernate. Instead of comparing a Butia and a Coconut, let's compare an alligator and a human. Humans body is basically as tropical as they get. It would be hard for a person to survive the latest spell of cold weather down here in Florida outside and naked. That's because we are unable to stop any of our vital processes for a period of time. We can't hibernate. Neither can a coconut. An alligator on the other hand, would perfectly fine for weeks in near freezing water, where a man would die of hypothermia within hours. When it gets cold alligators just start shutting down one system of organs after another, starting with the digestive system and ending with a complete shutdown. I think the same goes for cold-tolerant palms.

Martin I think you make a very good point about the drought tolerance, it's also a form of hibernation. A tree that hibernates well under one condition, can probably do so under another.

The problem is that palms don't hibernate (well, Trachycarpus might, but only Trachycarpus). Palms like Butia actually grow faster sometimes in the cold. Also, Butia and Coconut are in the same subtribe, humans and alligators are very distantly related. Humans can't survive in the cold not because they can't hibernate, but because we don't have fur. Animals like wolves who have a thick fur coat designed for winter are happy in cold.

I think it all has to do with "anti-freeze" enzymes present in the fluid of the palm, which probably makes it thicker in consistency and less likely to freeze. This could have to do with drought tolerance, as the fluid would still flow with less water present. Do we have any botanists here who might be able to explain to us what mechanism determines hardiness?

[Tyrone]

I think it has everything to do with the thickness of the cell wall membrane. Drought tolerant palms tend to have cold tolerance as well because a thick cell wall/thick stiff leaf will resist moisture loss when under drought stress. The cell walls are so strong, they can lock in the moisture and resist any cell wall puncturing. Plants that do not have to deal with any cold and live in constantly wet rainforests can have limp, soft cell wall membranes as they almost never need to shut the stomata's down for drought stress. These plants burn like hell in cold conditions because the expanding water inside the cells below 4C tends to exert pressure on the cell walls and bruises or totally punctures it. The leaf dessicates and it looks burnt. This is the typical cold burn. As water cools, it contracts until 4C, where it starts to expand again. Once it freezes it really expands greatly.

Cell walls can be strengthened by adequate amounts of potassium and calcium. On calcareous soils, calcium is not an issue, but potassium may be. Theoretically a potassium deficient palm will be more cold sensistive than a well fed potassium rich palm. Potassium deficient palms/plants have weak cell walls and tend to suffer in drought and hot drying winds due to the stomata failing to shut, and cell walls rupturing in extreme cases. Potassium deficient palms tend to have scorched leaf tips in hot dry weather on the oldest leaves first.

So my thoughts are that apart from plant genetics, plant nutrition has an enormous effect on the plants reaction to cold weather.

[Central Floridave]

Going on the drought tolerant equals freeze tolerant train of thought. Has anyone seen a difference on the same palm that has supplemental water versus one that lives on its own? For instance, a coconut with a sprinkler hitting it versus one that is in the yard with no watering? The one with no supplemental watering maybe adapted to drought a little better and maybe survived this freeze?

[Zeeth]

I think it has everything to do with the thickness of the cell wall membrane. Drought tolerant palms tend to have cold tolerance as well because a thick cell wall/thick stiff leaf will resist moisture loss when under drought stress. The cell walls are so strong, they can lock in the moisture and resist any cell wall puncturing. Plants that do not have to deal with any cold and live in constantly wet rainforests can have limp, soft cell wall membranes as they almost never need to shut the stomata's down for drought stress. These plants burn like hell in cold conditions because the expanding water inside the cells below 4C tends to exert pressure on the cell walls and bruises or totally punctures it. The leaf dessicates and it looks burnt. This is the typical cold burn. As water cools, it contracts until 4C, where it starts to expand again. Once it freezes it really expands greatly.

Cell walls can be strengthened by adequate amounts of potassium and calcium. On calcareous soils, calcium is not an issue, but potassium may be. Theoretically a potassium deficient palm will be more cold sensistive than a well fed potassium rich palm. Potassium deficient palms/plants have weak cell walls and tend to suffer in drought and hot drying winds due to the stomata failing to shut, and cell walls rupturing in extreme cases. Potassium deficient palms tend to have scorched leaf tips in hot dry weather on the oldest leaves first.

So my thoughts are that apart from plant genetics, plant nutrition has an enormous effect on the plants reaction to cold weather.

This makes more sense than any other explanation I've heard. Good job, you probably nailed it

[Tala]

extra K has been proven here to be of great benefit for combating cold. And fully agree with the drought tolerance, this proven time & time again but its also true we have plenty of extremely drought tolerant palms that possess no cold tolerance whatsoever. The hibernation theory also some merit, palms grown in slower Cal. conditions often can take lower temps than the same palms grown in a faster Fla. mode.

I believe that palms just like humans, insects, etc. can over eons of time either build or lose certain "tolerances or immunities" to various situations - cold, drought, lack of or reduction in pollinators, salt water intrusion, predators, human interference, etc. If these hazards don't kill them they make the subsequent populations stronger.

Some evolve into more complex species, and some fall by the wayside so another consideration are the individual palm's evolutions. It takes millions of yrs for each species to evolve and form. For instance the modern day Coconut palm has done a lot of island hopping over time, and while it appears to be more closely aligned with Syagrus than any other current genus its also plenty likely to have picked up traits from extinct palm genera along the way.

We are witnessing the beginning of some palm evolutions right now I think. The way Australian Livistona are evolving towards dioecism - is this to increase their populations as suitable habitats are becoming more isolated or reduced? Also the naturally occurring hybrids in close relatives of Cocosoids - again drastic habitat destruction or are changes in climate instigating this? Perhaps in a few centuries or less they will all be Syagrus???

apologies for all the wandering, no intention to hijack this, interesting questions always lead to others.