While hiking a remote section of the Navarro River in Mendocino County, I came across this unusual redwood towards the end of the day. It was a little ironic that Halloween was just a few weeks away when this tree made it’s spooky appearance in the afternoon shadows.
So how did this redwood come to develop such an odd appearance as if growing spider legs? At first glance it appeared that the tree was merely displaying exposed roots from a past flood. It did seem plausible that soil could have washed away from its base since the trunk did exhibit mud stains on the lower segment. After examining the tree’s surroundings, it was pretty evident that this wasn’t the case. The tree is situated within the upper section of the river's flood zone, but there was no evidence that a past slide or soil erosion scoured the base. Nearby redwoods around the same size didn't exhibit this unusual growth pattern as well. A closer inspection of the Spiderfork Tree revealed that these arachnid appearing legs were in fact old branches. All were dead, with most appearing to have died years ago. A few though exhibited some dead twigs and needles indicating that the last holdouts died recently.
With part of the mystery solved, the next question was why did so many branches develop in one section of the lower trunk? If the cause was from burl growth, you wouldn’t expect to see so many large branches perfectly splayed out at a 45 degree angle. Redwood burls sporting water sprouts usually produce a plethora of small vertical shoots. This is in contrast to the flared branch pattern seen on the Spiderfork tree. Active growing burls usually have a large amount of leaf litter associated with them as well. This makes their appearance seem ragged & less unorganized compared to branches. Other burls without waterspouts present, exhibit differentiated wood flowing like lava. None of this though explains why the tree displays such an interesting branch pattern.
Digging deeper, it’s hypothesized that this tree was sheared off in its youth around the location where the branch mass exists. Redwoods typically respond to the loss of their central leader by producing a mass of epicormic sprouts and lateral buds near the point of injury. These sprouts usually grow in a vertical fashion, racing upwards for dominance. This is because redwoods with a central leader produce a growth regulating hormone known as 'auxin' which suppress vertical development to all other parts of the tree. This form of growth control is known as 'apical dominance'. Without the hormone present, vertical growth becomes a free for all. In normal redwoods, eventually one or several vigorous shoots win out and become the new apically dominant leader(s). Less dominate shoots stop vertical growth and revert into branch form. In the case of the Spiderfork Tree, it appears that it was 'apically weak' for an extended period of time. No leader formed and instead the tree invested heavily in lateral expansion. So much so that an umbrella like canopy formed at one point in its life.
Following this period of lateral expansion, a few vertical shoots slowly developed. Gradually enough growth regulating auxin was produced by these new stems to effectively end the trees lateral dominance. Eventually they became the two codominant stems seen today. Over the years as the tree’s vertical height continued to increase, the lower portion became shaded out by the upper canopy. This in effect caused the slow demise of the lower branch mass. Today all that remains of the lower section of the tree is a skeletal remnant of how it once appeared.