Or, of course, alien plants might use some other pigment that’s more efficient than chlorophyll, whose existence we have no idea of.
Traditionally, biologists tried to divide life forms into two large categories, plants and animals. Broadly, plants made their own food and were not mobile, while animals had to eat other organisms and moved about. Organisms like fungi that were not mobile but which couldn’t make their own food were shoehorned into plants. (We now know that fungi are more closely related to animals than plants.) It was even harder to figure out where some unicellular organisms belonged. Green algae were assigned to plants, protozoa to animals, and bacteria were considered fungi and thus also plants. But there were still a lot of problematic organisms.
Today, biologists would consider plants to only include the Plantae, those multicellular organisms descended from green algae. Animals are the Animalae, which only includes multicellular organisms. Fungi are their own group.
Unicellular organisms, and some multicellalar ones including green, brown, and red algae, are not considered to be plants or animals but are classified in other groups.
I’m not following, here… Are green algae plants, or are they not?
There are mutated cacti that lack chlorophyll and can be white (actually slightly yellow), red or orange. (The latter ones still contain chlorophyll relatives.)
Originally found when seeds sprouted and didn’t come up green, but commonly propagated by grafting. They require a “host” green cacti to live on for nutrients and they can’t produce enough on their own. Even then they usually don’t live long. (The seedlings really don’t live long unless grafted onto a host.)
It would seem to me that if there was a type of plant that could make do with the red/orange stuff instead of chlorophyll, it would be cacti. Slow growing, lots of sun, etc.
So I think you pretty much have to be green*, a parasite, a decay feeder, etc., to have much chance of success.
- A lot of non-green plants have chlorophyll + another dye that masks the green a bit.
There are various definitions and concepts of the Plantae. The most restrictive definition includes only the multicellular land plants, and excludes green algae. A less restrictive definition (Viridiplantae) includes green algae (including unicellular forms) but excludes multicellular brown and red algae. The latter definition defines plants as:
Alien organisms might not even divide easily into the same caregories we have here.
True, I should have said “alien photosynthetic autotrophs”. Though even then, not all alien ecologies will even include that (life originated with chemosynthetes, after all).
Like an alien version of euglena?
Would these would be the autotrophs that have begun to drool?
What other energy sources might we find alien life hypothetically exploiting? Electromagnetic radiation outside the visible spectrum seems like an obvious one - and chemosynthesis we already know about. What else is there? Mechanical energy from wind or the motion of other fluids?
How about thermosynthesis?
If nanotech robots are the dominant ‘lifeform’ in the universe then mechanosynthesis, possibly driven by electricity, might be more common than photosynthesis.
There are a number of trees with leaves that are red year round. Some plants are parasitic. But red leafed trees can have green chlorophyll, masked by other pigments.
I’m not a British pea, but what he means is that since black is the color of things that don’t emit (generally by reflection) any visible frecuencies in enough amount for us to detect them, a plant that used all of the light it receives would be like a sponge for light, it would absorb all light, reflect none and be black. Greedy little plant… stares at her geraniums suspiciously
That site says that ‘Nigrescens’ is an evergreen…
its actually an everblack…
Possible changed OP for SD UFO readers way back when (I didn’t see the early-Earth time frame)?:
If it’s a plant, it must have purple stuff?..
Who needs chlorophyll when you have retinal?
There seems to be a lot of interesting pro and con info here–not dispositive, of course. Any comments from our resident board of reviewers?
ETA: strike “plant” above; insert…what?
Photoautotroph, probably.