I was procrastinating on Wikipedia and reading about plants and things.
I notice there are many species of cold-resistant plants that grow in warm places, and CAN grow in northenr/colder places when someone plants them their, but they never grow on their own.
Like the American palmtress, Filferia, and sabal palmetto can occasionally be seen growing in someone’s yard in cold places, but they’re usually rare.
Both can survive temperatures well below freezing, but they’re rarely seen outside of places in further north than 38 degrees.
I notice the same thing for just about all cold-hardy palm trees, yuccas, and anything else that’s evergreen and isn’t a pine tree.
For one thing, I doubt whether most of the plants you are thinking of really thrive in colder climate, even if they can survive there with human help. Even if they can survive on their own in the cold, they may not be able to reproduce.
Secondly, they have got to get there from wherever it was they first evolved, and plants can’t walk by themselves. Of course, they can spread by setting seed, but various geographical barriers, such as mountains and seas, areas of desert (or any area of land unsuited to that particular type of plant), even large rivers, can get in the way of that.
Many plants that are reasonably cold-hardy as mature plants are more sensitive when young. In a warming climate, many of these which were used as ornamental plants in gardens for centuries have started to be able to propagate and invade the forests, e.g. in southern Switzerland (laurophyllisation in switzerland)
Yep - the context of a garden is less competitive than the wild, more sheltered (in general terms, not just weather), more managed for pests and problems.
And also correct on the reproduction. Some warm climate plants will grow in colder places, but never flower, or may flower, but too late in the season to set seed, or the required pollinator may not be present, or they may flower and set seed successfully, but the winter conditions are not conducive to its survival/germination, or a specific seed vector (such as a bird big enough to eat the fruit and weaken the seed coat) may not be present.
There’s also the issue of competition. A plant may be able to survive in a colder climate than its home range, but to spread there it has to compete with plants that thrive in that climate.
ETA: Which Mangetout touches on, but I think it bears singling out for emphasis.
Agreed - if we consider any given plant species to have a range, then typically within the middle of that range, it is able to compete properly, reproduce properly, cope adequately with the climate etc.
Toward the fringes of the range, those optimality factors start to tail off - it isn’t usually an abrupt transition - more of a statistical thing - but it means that fewer and fewer really thriving specimens exist of that species, but more and more of some competitor are doing OK.
It’s not like that for everything; some things (which will often be labelled weeds) grow almost anywhere; some things could do extremely well in another zone/region, but for one reason or another, never got the chance to try (these may become invasive species if introduced to that different region)
Pine trees are a common plant in the Southern USA. There aren’t many in New Hampshire, I learned upon traveling there. I’ve also seen how badly they fare in a heavy snow or ice storm. I wonder if having foliage in the Winter is a detriment in cold climates.
I think this, combined with the fact that enough of the population has to withstand whatever occasional low-temp excursions to remain viable.
For example, Valencia oranges can survive 10 hours below 25 degrees Fahrenheit, and don’t like it much below 35 F.
This means that most of the time, they’d be fine somewhere like Houston, but every now and then (like every 25 years), they get a cold snap where the temps stay below freezing for a few days and the temps do get as low as 25.
So in the short term, my father can plant citrus in his backyard and have it thrive, but eventually, it’ll get killed due to cold weather. In the wild, these plants probably would get out-competed in short order by plants that aren’t kicked in the ass by cold so badly.
In silviculture more emphasis is placed on a plants niche rather than range. In its simplest form, a forest stand is not made up of communities of trees growing in their optimal environments but rather trees growing where they can outcompete others. A tree’s niche is where it does grown, not where it can grow, or even where it grows best.
This is why you end up with odd situations such as lodgepole pine in western Washington. Within the optimal sites for lodgepole pine growth it is always outcompeted by Douglas-fir and red alder. But lodgepole has a really broad range so its niches are the wettest sites, the driest sites, and the highest elevation sites. It will never grow optimally, it will always be a slow growing, stunted, twisted looking thing, but it will survive.
By sheer coincidence :dubious: I was reading last night about bald cypresses, whose natural range covers a large swath of the southeastern U.S., up as far north as southern Illinois and Indiana and over to the Delaware Bay.
Bald cypresses are fully hardy much further north, all the way into Minnesota and Ontario. As explained in the text (Native Trees by Sternberg and Wilson), seedling bald cypresses need a constant supply of surface moisture until their roots have developed enough to get below the water table. In warmer areas, swamps and seasonally flooded places supply enough water for young trees to grow. In the north, these wet spots freeze over in the winter and ice kills the seedlings.
However, in a northern garden or other controlled setting with attention to watering, seedlings/saplings do fine. I planted a couple of bald cypresses in my front yard about eight years ago and they have flourished, tolerating last winter’s multiple subzero lows (and a drop to -19F) with no problem whatsoever.
*and yes, I know bald cypresses are not evergreen, but are one of the relatively few deciduous conifers.
I remember visiting Italy about a decade ago and it seemed that bamboo stands were growing everywhere, despite the fact that bamboo is (AFAIK) a tropical plant and Italy can get snow. I assumed it was a decorative plant gone wild.
The advantage of dropping leaves in winter, as opposed to evergreens, is that the plant does not have to have “hardy” leaves that survive the cold. You can feel the difference between needles and soft seasonal leaves; they also have the area to capture more light, and are wetter relatively (no freezing issues) so can process with photosynthesis more easily. Green leaves are a waste of effort in the winter as the frozen leaves won’t do much photosynthesis anyway, if the raw materials and the finished carbohydrates have to be transported by water. The plant is dormant, the leaves aren’t doing anything. Thin needles are less likely to be damaged during the dormant, cold, brittle times of winter than wide spreading leaves - so there’s also the “repair” aspect needed for flat-leaf evergreens.
Pine trees have the advantage in less fertile, more marginal climates where the soil is less fertile or the climate is drier and so growing fresh leaves every spring can be a disadvantage; or further north, where the growing season is shorter and the advantage of wide, flat leaves does not make up for the time and effort needed to re-grow them every year.
I suspect the evergreen quasi-tropical plants you are thinking of are adapted more for occasional cold spells than wide open full on winter where below freezing lasts for months.
