Thank you guys. Just... in school, "a couple of days ago", I learned it
the other way round for trees. I remember as it did impress me vrey much.
The trees leaves would be red, yellow or white if it were not for the chlorophyll. This is why they look those colours when leaves start to unfold & grow, in my region usually in spring.
Then the tree adds the chlorophyll to the leaves & they look green. This is the look of our summer. The trees usually are quite quick in adding the chlorophyll, they want the leaves to take part in photosynthesis.
In our autumn, the trees drag back their precious chlorophyll to store them for the next year. Now we see the fullgrown leaves "in their own colours", ie. red, yellow or white. Then we have the lovely colours of our autumn / fall!
When in our autumn the tree has taken everything it needs from a leaf, it cuts off the leaf from supplies. Then the leave falls, turning bristely dry & brownish.
In tropical regions without such seasons, I would expect this cycle to happen all year round. We didn't talk about that, back then.
Now those
cacti on the other side, they really take some time with their all-over-red stalks until they fill them up with chlorophyll. During that red period, which might go on for a fortnight or longer, those stalks need a lot of energy to grow but do not produce any energy at all -- no photosynthesis without chlorophyll.
Never have I seen such a behaviour in other cacti, eg. Mammillaria or Cereus. Their new cutlings have chlorophyll & thus produce energy from the very start, when I discover them for the first time.
Some grownd dwelling succulents as some Haworthias (H. trucata is a good example), they only show colourless, transparent "windows" of their stalks in the surface. The precious chlorophyll is hidden inside the stalks in the gound, where the plant also is protected from too much heat & evaporation. But when a new stalk is formed at my H. trucata, which is not hidden in the ground, I always see it in green & thus taking part in photosynthesis.
So I can't understand what those Epis gain from this elongated, unproductive "childhood" of a stalk?
I sincerely hope my question becomes clearer.
N.
Following you, the only thing that I can understand being protected, would be the chlorophyll. But why should it be protected in the new stalks & not in the old stalks?
I can't understand this.