In the park

Not the normal park, but the one a little further away which is home to some lovely trees. The one I have focused upon in this video/slideshow is, I think, a plum and I choose the tree because they are quite remarkable. The main trunk is hollowed out and rotted, with a fungal growth that looks like a paint spill. I found it stunning.

Now, I have been reading a fascinating book by Francis Hallé called In Praise of Plants. It's a great book, and is very funny in places, with plenty of excellent diagrams. It also goes into a great deal of detail. And here are two things I have learned but may not be able to explain.

Plants require two generations to make, as it were, one plant: the gametophyte and the sporophyte. In polypody ferns, these are two distinct and independent beings. The plant we assume to be the plant is the gametophyte and is diploid (with two copies of the DNA). But, it seems, in many plants, the haploid sporophyte is the main plant and the gametophye is like a kind of parasite!

Plants do not separate the germ-line and the soma-line, as animals do. So while an animal's life experiences don't change the animals genome (epigenetics aside - that might have been studied after the book was written), a plant's meristems (the growing tips) are essentially also its germ-line and any mutations of cell division will pass into the body of the plant and the next germ-line. If you see what I mean. The argument is that on a large plant, different parts of the crown (on the same tree) can be genetically distinct - and thus, say, more or less susceptible to pests.

There's so much more, but I struggle to wrap my mind around some of it. What it all suggests though is really interesting because it's like each bud is the parent of a new plant that basically does it's own thing. A branch, unlike an arm, is doing its own thing - seeking light, principally. So, is a tree a community of individuals? All those branches 'competing' with each other? That doesn't quite work. A tree will drop a branch that's not, er, pulling its weight, in a drought, say, so does that suggest there is some central organisation? Or that the branch can't compete for the shared resources pulled up from the roots?

Whatever, it maybe explains why - and there's more to this that I won't go into - a shoot from the trunk can 'create' a new tree even when the crown has died.

An extended quotation, now, which is thought-provoking:

Certainly, animals must accommodate themselves to physical laws, but in ways appropriate to them. From the fact that they are mobile, they flee from difficulties rather than submit to them. Perhaps animal evolution can be presented as an increase in the number of degrees of freedom, leading to acquisition of more and more complete autonomy from the constraints of their environment (Favre and Favre, 1991). On the contrary, plant evolution would be adaptation more and more driven by hard reality, with more and more complete integration into the environment (Rose Hébant, personal communication). Animals present images of their own freedom; plants, more modest, express the constraints of the environment...

Francis Ponge (1942) spoke of trees: “They are only an expression of will. They have nothing to hide for themselves; they guard no secret idea, they arrange themselves entirely and honestly without restriction... , they only occupy themselves to accomplish their expression: they prepare, they decorate themselves, they wait for someone to come and read them.” Réné Thom (1988) was scarcely more prosaic: “One fundamental constraint for the dynamic animal, which distinguishes animals from plants, is predation... Plants do not have specialised prey, thus they always seek to identify with a three-dimensional milieu.” For plants, “We find a sort of fractal dilution in the nourishing ambient milieu.” Perhaps the transcendence of animals, including humans, is mirrored by the immanence of plants. (Hallé 2002, 281–82)