No Trespassing!
This is one of the first brooms I found- on a Pinus contorta var latifolia tree in WA. It was right on the side of the road on a busy highway. Since the branch was hanging over the ditch (public right-of-way), I figured that it was fair game. My dad and I stopped by with a pole pruner one December morning several years ago and got some cuttings. It was oddly brittle, and sizable chunk broke off. In fact, the dead portion on the front is from where it broke- this pic was from a year or two later.
I had half a dozen rootstocks at home, and grafted them up. Not a single graft took. The annoying thing about conifer grafts is that you must wait for several months to find out if you were successful or not. The grafts can look wonderful until the first warm days of late spring. Then they can suddenly die.
Still others might live- but the new buds have all died, so it will never grow. Such a graft dies within a year or two.
I had to try grafting this tree about three times before getting one graft to take. It still grows in my garden today. Here's a picture of it from a couple of years ago:
As you can see, it has kept its congested growth pattern. Its ultimate form remains to be seen. It may or may not look like a tiny replica of the original broom.
The last time I collected scions from the broom, I got a few tiny pine cones. I had read that broom hunters will sometimes germinate the seeds- roughly half of which will produce dwarfed offspring.
The trouble was the cones were glued shut with resin. Lodgepole pine is a species that is highly dependent on fire. It is shade intolerant, so it can only regenerate in sunny positions. Because of this, it has a number of adaptations to both encourage fire and reseed afterwards. Mature lodgepoles contain a lot of dead wood in their canopies- they actually are adapted to encourage the fires that almost inevitably killed them in pre-settlement North America. These fires were often hot enough to kill all of the trees in stands, leaving a charred landscape devoid of trees. Such landscapes are perfect for pine seedlings...
In addition to dead wood, lodgepole pines build up large reserves of cones that are sealed shut with resin. During the heat of a fire, the resin melts and the seeds fall to the ground- onto the freshly fire-prepared seedbeds.
Alas, I digress. What this meant for me was that I had to melt the resin to get the seeds out. I did this by dry-roasting the cones briefly in the oven- just long enough to get the cones to open.
I managed to get two seedlings out of the deal- one of which is clearly dwarfed. I'm still not sure about the other one. Time will tell.