I performed an unintentional experiment this past winter. One of my neighbors purchased a bunch of worm castings for her garden. She used what she wanted then gave me a 1/2 gallon ziploc bag full of the rest (neither this blogger nor the parent company of this blogger endorses the use of ziploc or any other trade name plastic resealable bag). Actually it might have been a glad bag. In any case, upon first inspection it was clearly crawling with little red wiggler worms (this blogger, though probably not the parent company of this blogger, whole-heartedly endorses the use of Eisenia fetida for the disposal of rotting vegetables). I set them in the mud room and proceeded to forget about them. After a while some very small weeds germinated then the frost killed them. The bag stayed out in the mud room all winter and was subjected to numerous freeze thaw cycles.
This spring the plastic bag resurfaced. The boss did not approve, but I wasn’t ready to add it to the garden so I just let it fester. I figured it would be like a speck of sand in an oyster and would slowly accrue a pearl around it.
This didn’t happen. What did happen is some plants eventually germinated. I say “some plants” because I really don’t know what they are — it might be purslane, that’s what the stems look like. But the leaves are wrong.
And a closer look:
The leaves look kind of tomatoey, but the stem isn’t hairy enough. I really don’t know. But that’s not why I got interested in this. It reminded me of seed dormancy.
When seeds are created in a plant they have to wait for the right conditions to germinate. But that’s not all, just giving them the right water, temperature and sometimes light won’t always do the trick. Almost all plants have evolved so that they wait to germinate until they fall off the parent plant. Some mangroves, though, exhibit vivipary and germinate before falling into the water. I guess humans are that way too, though thankfully we don’t usually fall into the water right away.
Most plants want to send their offspring away so they use wind, beast or water to spread the seeds. This is not so much like humans. There are others I wish the wind would take away. Bye bye Boehner. Once the seeds get to the perfect habitat, though, many plants need to build in a delay. For most, this just means the seeds need to wait until they get some cold. The seed says, “ok it’s winter, I’ll get ready for spring,” then once temperatures warm off they go.
Jack pines a smallish western tree (small in the west means less than 80 feet tall), has waxy cones that stay on the tree until there’s a fire. Once scorched, the seeds are released and primed to take over the newly burned soil. Very clever.
Dormancy can allow seeds to last many decades until the right conditions have transpired. Several years ago I saw a talk given by a biologist from the University of Kentuky Carol Baskin. She had a space set aside in a green house where she and her lab group had placed some square meters of soil in containers. They watered them periodically, but otherwise left them alone. Every fall they collected the dry matter that grew. They had been doing it for more than ten years and every year plants kept germinating. The soil formed a sort of seed bank.
No matter how much you weed they’re in there waiting for you. When you turn your back, they germinate. Luckily, pulling weeds is a great joy.
