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Humans care about wood, so they made tree (thing which produces wood) a category, as it can be used to build bridges, ships and other structures. Wood being de
by photochemsyn 4y ago
Humans care about wood, so they made tree (thing which produces wood) a category, as it can be used to build bridges, ships and other structures. Wood being dense also made it a better feedstock for charcoal (one can use grass, however).
As far as why trees don't seem to evolve into grasses, (or grasses into trees), it might be all about C3 vs C4 carbon metabolism, the latter being a complex structural system that pre-concentrates atmospheric CO2 before feeding it into the photosynthetic biochemistry (which is the right way to do artificial photosynthesis as well). This is apparently difficult to do in trees?
https://pubmed.ncbi.nlm.nih.gov/32409834/ https://pubmed.ncbi.nlm.nih.gov/32409834/
> "Since C4 photosynthesis was first discovered >50 years ago, researchers have sought to understand how this complex trait evolved from the ancestral C3 photosynthetic machinery on >60 occasions. Despite its repeated emergence across the plant kingdom, C4 photosynthesis is notably rare in trees, with true C4 trees only existing in Euphorbia."
And here we have the world's largest Euphorbia:
https://www.wikidata.org/wiki/Q5851367 https://www.wikidata.org/wiki/Q5851367
- jameshart 4y agoBamboo being the obvious exception of a grass that really wants to be a tree.
- mankyd 4y agoAnd Palm "Trees".
- throwawaylinux 4y agoPalms are not grasses.
- mankyd 4y agoIs that true? Most of the internet says they are, and I first learned it from a local guide several years back.
- jacobolus 4y agoPer Wikipedia, under the clade commelinids there are 4 orders: Arecales (palms) Commelinales (spiderwort, water hyacinth) Poales (grasses, rushes, bromeliads) Zingiberales (gingers, banana) So depending on how you measure, palms and "grasses" are distinct but closely related groups of plants.
- shagie 4y agoAll grasses are monocots (single part seeds) - https://en.wikipedia.org/wiki/Monocotyledon https://en.wikipedia.org/wiki/Monocotyledon and its got things like corn, oats, lawn grasses, wheat, horsetail grass ... and sugar cane, bamboo, Joshua trees, and palm trees.
- PaulHoule 4y agoThe big split between flowering plants is between monocots (grass, palm trees) and dicots (say a Rose bush and a Apple Tree.) You can find non-trees and trees that are monocots and dicots and also non-flowering trees and non-trees for that matter. The main issue is that when plants get big they get woody and take on the characteristics of trees. I like the irony of that title that a "tree" (in the computer science sense) is the basic unit of phylogeny with the caveat that it is broken at the top because the three operating systems for a cell are described here https://en.wikipedia.org/wiki/Domain_(biology) https://en.wikipedia.org/wiki/Domain_(biology) they do show a tree on that page based on a particular set of genes but if you picked a different set of genes you would get a different tree because complex cells have a mixture of Archaea and Bacteria because they merged in some horizontal gene transfer event long ago.
- hammock 4y ago>As far as why trees don't seem to evolve into grasses, (or grasses into trees) They are different branches of the tree of life. Dicots (trees) vs monocots (grasses)
- thriftwy 4y agoPalm Tree is monocot, and it is a notable tree. A lot of grasses are dicot, any one with ornate leaves (monocots have blade-like leaves).
- dboreham 4y agoPalm tree is not very useful for structural wood.
- thriftwy 4y agoBamboo is monocot, not a tree, and is highly useful for structural wood. These are all orthogonal.
- deleted 4y ago[deleted]
- hammock 4y agoOnly with a lot of glue added or as entire culms
- RosanaAnaDana 4y agoTell the pacific islanders that.
- 0_____0 4y agoIdk if you've dealt with palm wood but most of it is very very soft. You would not want to try to do anything you would recognize as structural framing with it.
- RosanaAnaDana 4y ago>As far as why trees don't seem to evolve into grasses There is obviously no non-teleological answer for this, but it can be much much more straight forward than metabolism. Think of plants as basically solar panels. We can think of the 'grass' phenotype as competing through r-type selection. Lots and lots of individuals, lots of surface area, short life cycles. Short bursty growth, convenient loss resilience, easy mobility. 'Trees' are the also optimizing for surface area (among other things), but are relying on k-type selection. Longer life-cycles, lower probability of successful reproduction, specialized pollinators, and very significantly, vertically stratified growth habit. Being an individual in a k-type species is like a very significant advantage for that individual, since its unlikely that the vast majority of k-type seeds will successfully reproduce. Being k-type may not be more competitive for the species overall, but it may result for a selection bias at the individual member resolution, and so may be unlikely to be selected against. There are many many advantages to lignification when your whole thing is basically being solar panels on a pole. It would seem extremely unlikely this has anything to do with metabolism other than 'doing more of it'. We already know why monocots don't make trees more significant than palms (read: vascular bundles and eusteles). My money goes to species level versus individual level selection in k versus r.
- maxerickson 4y agoLots of trees are wind pollinated. It's one of the reasons pollen season can be unpleasant.
- andrewflnr 4y agoWhen I see the ground under an oak tree covered in acorns, most of which will be food, my first thought is definitely not that the tree is engaging in k-selection.
- WalterBright 4y agoThe tree relies on squirrels to disperse the acorns (hiding them and then forgetting where they were buried, or being eaten by a grue before retrieving the acorns). Fruit is another common way to disperse seeds. Animals & birds eat the fruit, and then disperse the seeds with a dollop of fertilizer (poop). Lots of co-evolution going on.
- go_elmo 4y agoHave you considered evolutionary selection as reason for c4 not being adapted by trees? Grasses profit much more from growing quick than trees, where new opportunities (e.g. trees dying, fires etc) are rather rare & being able to grow extremely quickly wouldn't provide much of a benefit?
- justinclift 4y ago> ... being able to grow extremely quickly wouldn't provide much of a benefit? After any substantial ground clearing event (eg bushfire, etc), wouldn't the subsequent "winners" be those who grew the fastest to capture the available sunlight + suppress their competitors?
- thriftwy 4y agoThere are multiple waves of succession in trees. So no, being the first does not give you a clear advantage. https://en.m.wikipedia.org/wiki/Ecological_succession https://en.m.wikipedia.org/wiki/Ecological_succession
- WalterBright 4y agoSo true. I live in an area that was clearcut a century ago. The battle of the first movers vs the usurpers is well underway if you know what to look for. It's a fight to the death, in very very slow motion.
- justinclift 4y agoThanks, that's interesting. :)
- finiteparadox 4y agoIf tree is a category, does it have limits?
- behringer 4y agocame here for the grassy tree, not entirely disappointed.
- onos 4y agoIs green a color? There is a continuous set of colors between green and blue, but when I see a green I often know it.
- lathiat 4y agoMy wife and I disagree quite strongly on the crossover point fairly consistently. I also saw some research showing a supposed gender gap in that observation. Whether or not the gender part is true it seems very much that different people crossover some of these at different points.