How do I patch this hardwood floor strip?

Question

I live in a >100 year old apartment building with a lot of temperature variation and the hardwood herringbone oak flooring is starting to show its age. What is the best way to patch this spot where two strips meet? Each strip is 2.5 inches wide and 18 inches long. The end of one strip was at some point cleanly cut in the past, and now the strip that is laid perpendicular to it has cracked. I would rather fill in the gap with a temporary solution than will get me by for a few years than do something more permanent like replacing both strips.

Here is the general area:

Closer view:

Side view:

Two more from the top:

By the way, that little white fleck is a grain of rice, not an insect.

Answer 1

I'd gently lift the cracked strip into its original position, then fill under and around it with a stainable, hardening wood putty. Once it's cured, stain it to match the lighter color in the wood grain. Use a permanent brown or black felt pen to simulate the dark grain.

Answer 2

As @isherwood mentioned, wood putty is the standard patch for this type of issue. Assuming the subfloor is sound, any hardening wood putty should work, and you can find them pre-colored in many stores.

Fill the putty into the hole, including under the splintered piece to support that. For a more finished look, sand it smooth after the putty dries and coat with some polyurethane (brushed on in the direction of the wood grain, and feathering out to blend with the existing finish).

You may need a couple of passes to properly fill the hole with putty, because putty can shrink as it dries.