TWO SPECIES OF WOOD IN A SINGLE SLAB - VERY UNUSUAL polished petrified wood

Description

Dogwood root and rootlets of a conifer species
(Cornus sp.
Pinales order
)
Mehama Volcanics Unit, Little Butte Formation, Oligocene
McQueen Ranch, Sweet Home area, Linn County, Oregon
Wait -- that is not dust in our photo!
Read on ...
Take a good look at the macro-photograph and notice two things:  first is the circle inside a diamond structure at the 6 o'clock position (there is also one of these at the 7 o'clock position).  Second is the multitude of very small but different sized, oddly also diamond shaped structures that occur in several places on on this slab and make it look like we did not dust it off before photographing it!   Each of these odd little structures is a rootlet of a totally different species of tree (the two larger ones would qualify as a root rather than a rootlet).  The overall specimen itself is a root of a dogwood-like tree
(Cornus sp.)
The other small structures are not Cornus sp. - they are a species of conifer.  So, there are two different species of wood in this single slab.  It is not uncommon for wood from some of the Columbia Plateau Flood Basalts to have penetrations of roots through a rotting log.  But those are almost always roots of a tree that are growing through a dead and down log buried under the duff of the moist forest floor, where the log being penetrated is beginning to decompose.  It is easy for new plants growing above it to simply penetrate the rotting log.  Often the resulting petrified slabs are called "forest floor" or "bog wood.” But the specimen in our photographs is the result of a
completely different
taphonomy.  Notice that the small structures are actually a circle with one triangular attachment generally pointing towards the center of the slab and another triangular attachment, directly opposite, generally pointing towards the periphery of the root.  These triangular features are there because the dogwood root is growing outwards and engulfing the smaller roots which are already firmly anchored in the ground.  But the smaller rootlets are in the path of the faster growing dogwood root and not able to “get out of the way” when the faster growing big root approaches.  As a root grows, it puts on new cells in the cambium layer and as those cells develop, they push the dirt away from the periphery of the growing root.  The strength of a growing root can easily be seen in many towns where sidewalks are being pushed up and out of position by the roots of adjacent trees.  So, while it is relatively easy for a root to push away the surrounding soil (both the mineral matter and the vegetative humus), realistically it can only push in a single direction - parallel to the rays (or perhaps better said, perpendicular to the growth direction of the cells in the cambium).  As the dogwood root gets closer and closer to the smaller rootlet, it begins to encounter difficulty pushing the dirt that is immediately up against the smaller rootlet and the dirt poses an impediment to continued cell development in that sector of the cambium.  The strongest resistance is encountered in a plane directly running through the center of the opposing rootlet and that spot is defined by the tip of the triangle pointing towards the center of the dogwood root.  That cell of the dogwood is unable to push any harder.  Soon, the adjacent cells encounter similar resistance when they are the same distance from the rootlet and that process is repeated over and over again, until finally the faster growing dogwood root is able to bypass entirely the slower growing small rootlet.  The result is a triangle of soil still remaining but enveloped by the dogwood root.  Cambial development then continues in a normal way while the dogwood passes by the largest diameter of the small rootlet.  But then after passing this point, there is not a cell immediately available to push away the dirt on the other side of the smaller rootlet.  Cambial cells can reproduce sideways as well as in a forward direction, but not at the same pace as the forward movement.  So, as the faster growing dogwood root advances, it gradually begins to push away more and more of the soil in a sideways direction until finally the sideways cells from both sides meet and reform a complete root growth pattern in the dogwood.  This defines the tip of the triangle of the dirt pointing towards the periphery of the dogwood root.  The process envelops the smaller rootlets and makes it difficult for them to grow much larger or even function.  Since they died before the dogwood, they tended to rot out soon and thus don't have very good wood anatomy preservation although the root at the 6:00 o'clock position has just a bit of tracheid preservation at the edge as can be seen in one of our photomicrographs.  We are also showing a photomicrograph of really tiny hair rootlets that provide almost no impediment to the faster growing dogwood.  There are dozens of these tiny rootlets scattered throughout the slab and show up on our photomicrograph as rather light colored circular structures, so as we said, those are not dust in the picture!  This is a fascinating piece with a unique story to tell!  It measures
5” x 4.5” on the polished face and is a slab 3/8” thick.
If you value uniqueness and a slab with tremendous "conversation starter" potential, this is one for you.  Lots of collectors have roots penetrating forest floor in their collection.  specimen of one species of root overtaking another species is not often seen because it is indeed a rare occurrence in the fossil record.  We specialize in petrified wood and plant fossils which are accurately identified as to locality of origin and family, genus or species. We don’t guess and when we don’t know, we say so! Your specimen will come with a label identifying the specimen, the locality where it was collected, the formation and age of the material and any other pertinent information we have gleaned from our literature search.
Buyer to pay shipping charge of .50 for delivery to addresses in the United States. We are happy to ship internationally but international bidders should use the eBay postage rate calculator before bidding to determine postal rates for the postage charges to their country.
Be sure to check out our other auctions. We are happy to combine auction winnings to save you shipping costs.
eBay is now
charging
and collecting State Sales Tax for many states and yours may be one of them.  eBay then remits the tax directly to your state tax agency.
Powered by
eBay Turbo Lister
The free listing tool. List your items fast and easy and manage your active items.