amber wood

Which tree produced the Baltic amber resin?

Sorry, but a still rough English translation follows!

Debris of wood are very abundant in amber, though not liked by collectors. What is still recognizable, are splinters of coniferous wood. I do not know any rsplinters of angiosperm wood in Baltic (and Bitterfeld) amber! Most of those wood debris are the result of activity of insects resp. insect larvas. Therefore these wood debris flown out with the streaming resin are the most abundant and important remains of the amber trees.

Which other parts of the amber coniferous trees could have got into the resin and remain enclosed in it? Parts of bark, if not too large; pollen dust; male flower buds or parts of it, needles resp. leaves - bigger parts like cones derived form female flowers do not remain stucked to the resind and will not be enclosed completely.
But there seem obvious contradictions: wood and pollen grains looks like pine, but the chemistry of the amber looks like resin from araucarias, and needles resp. gymnosperm leaves are much less included as normally expected.

Concerning the resin chemistry, there are newer dicovery results about the fact that resins change so much during and after becoming amber, that they are comparable to species of living trees only in a very restricted manner. Except of that. at least one of the still living pine species, which has a resin composition very different from the rest of pines and has some similarities to Baltic amber. So resin chemistry appears to be not so well suited to identify the amber tree. Angiosperm resins like Doninican and Mexican amber can be excluded at least. (Between Baltic amber however, there can be found some rare pieces representing fossil resins coming form other plants than normal.)
The majority of flower dust (pollen) is most similar to pine pollen. Also the parts of male flowers, which are not so rare in amber, seem to represent pines. But also much pollen of gymnosperm and angiosperm trees and brushes is found in amber, representing plants which grew in the vicinity of the amber trees, but produced no resin at all.
Leaves and needles in amber lead to a curious impression: Small elongated gymnosperm leaves are not seldom, but they derive certainly not from pines. Other leaves come from thuja or cypress plants. Needles and its remains are rarely enclosed in amber, and they are diverse, part of them representing more fir (abies) needles. Possibly the amber tree had needles so long as the Canarian pine or the Caribic swamp pine, which have nearly no chance of preservtion in amber because of its length. Pieces of bark with its characteristic cork tissue are not rare, but can come from any conifer.
First of all let us have a look at a microscopic sketch of typical Baltic amber wood:

Reconstruction sketch of amber wood, changed by me after a Vorlage from R. Wagenführ. Direction of growth from the interior (front left) to the exterior (behind right) according to the arrow. A bit more than one year's groths is shown.

Above: Cross section with resin channel (yellow) and wood ray (brown). The early wood consisting of broad longitudinal tracheids is light coloured, the late wood darker ("quer" means cross-section).

Tangential view with wood rays, one of them with a resin channel. Brown: wood ray parenchym cells, blue: transverse tracheids as components of the wood rays.

Radial view with a wood ray consisting of parenchym cells (living storage cells, brown) with simple pits and of two transverse tracheids (blue) with small bordered pits. The longitudinal tracheids (vertical) of the early wood (lighter) have big round bordered pits.

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Too much technical terms? No idea, how active gymnosperm wood "works"? So I will try to give some general explanations (wood specialists may forgive me for my simplifications!)

Gymnosperms are a plant class consisting of cycads, ginkos, yewtrees (taxus), thujas, cypresses, redwoods and conifers. Gymnosperm wood has no continuous vessels (trachees), but extremely elongated vessel cells (longitudinal tracheids), which are situated vertically in a tree trunk and which are used for transporting liquids and nutritional solutions together with parts of the bark except they have become part of the core wood. The upper most part of gymnosperm wood consists of tracheids. Its more or less massive walls are responsible for the strength of the wood.

A tracheid is a very elongated cell, but closed on all sides - how can it help to transport liquids? Tracheids are dead cells - its contents are decomposed, they are so to speak empty. But they are connected to the neighbouring cells by so-called "pits", better by pairs of pits. A pit is an area of the cellular wall so thin that liquids resp. nutritional solutions can pass. Towards neighbouring tracheids, bordered pits (sketch left) are formed, both tracheids forming one half of the pit pair (red and green). A thickened section (torus) in the center of the membrane may shut the bordered pit constantly or temporary under certain circumstances. To the right, a simple pit pair as usual beteeen living cells (according to Wagenführ, modified).

So far, transport and compensation of liquids is guaranteed in a concentric ring of neighouring tracheids. But in coniferous wood with resin channels like amber wood there are no pit connections between such a ring of tracheids to the next older (inner) or to the next younger (outer) ring of tracheids - therefore there are no pits in the tangential view in the sketch above. The liquid compensation between the inner and the outer tracheids is managed by parts of the wood rays, which wise transverse to the longitudinal tracheids from the center outwards (sketch above). If the coniferous wood has resin channels, the wood ray consists of transverse tracheids and wood ray parenchym cells which are alive and able to store nutritional substances.

Normally the outermost cells of a wood ray are transverse tracheids. Like the longitudinal tracheids, they are dead cells and according to that they have (small) bordered pits. In many pines, but not in amber wood, the transverse tracheids have conspicuously jagged membranes. In gymnosperm wood without transverse tracheids, the longitudinal tracheids bear some bordered pits also on its tangential sides, so that a liquid regualtion between the different rings of tracheids can take place.

Wood ray parenchym cells are living cells with plasma and core. They are connected to each other and to the tracheids by simple pits (not bordered pits). Even in amber the darker colour of those parenchym cells is visible occasionally, possibly caused by deposited nutritional substances.

There are vertical resin channels between the tracheids and horizontal ones within thicker woodrays consisting of several layers. Resin channels are surrounded by special cells producing resin.

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Amber: A Perfect Fossil Trap
The Living World in Amber (1)
The Living World in Amber (2)
The Micro World Embalmed in Amber
"Atlas of Plants and Animals in Baltic Amber"
Amber Internet Links
The Amber Dictionary from A-F or G-Z

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