Wednesday, May 20, 2015

Harvesting Draba Seeds

This could pass as a Martian landscape, but it is actually a portion of the seed I harvested today from my container grown Draba cuneifolia.

The container was so crowded with Drabas that the flower stalks had woven into one great mass.  Any attempt to harvest seed from one plant caused all of the neighboring plants to dump their seed load.  More than enough seeds had already fallen back into the container, so I had to find a harvest method that could effectively remove the remaining seeds from the plants without additional losses.

The Draba seed pod is divided into two halves with a thin, semi-transparent membrane running through the center.  Seeds are arranged in two rows on each side of the membrane.  When the seeds are ripe, the two outer coverings of the pod begin to peel back at the bottom, leaving the seeds exposed.  At this point, it doesn’t take much disturbance to cause the seeds to fall free.  In the past, I have harvested seed by simply bending the plant over a small cup and giving it a couple of taps.  The seed fell into the cup and that was all there was to it.  That method doesn’t work when the tangled plants all acted as one unit.

I decided to try using my shop vac as a harvester.  My shop vac is a bagless model, so I took a clean sweeper bag and modified it to fit the inlet pipe on the inside of the shop vac dirt chamber.  Then I directed the sweeper hose towards the plants and the seeds quickly disappeared.  The shop vac is not a high end model, so the air flow past the plants was really kind of gentle and did little more than pull away loose parts.  I just hoped everything was ending up in the bag. 

Fortunately, the sweeper bag stayed in place through the entire operation.  I sucked in a lot of seed pod covers, along with a little bit of dirt, but it looked like there was also some seed in the collection.

A closer examination revealed plenty of seed hidden beneath the seed pod parts.

I had to cut the sweeper bag in half to remove the seeds, but I was happy with the harvest.

Draba seeds are tiny things.  That’s a normal sized nickel beside the seed pile.

This is what I ended up with after sifting the mess through a screen to separate out the seed.  That’s five grams of fine Blue Jay Barrens Draba cuneifolia seed.  I couldn’t find any figures specifically for Draba cuneifolia, but similar Draba species average about 6,000 seeds per gram.  That means there are 30,000 seeds in this vial.  I’ll be scattering this seed back on the barrens in the same area from which I originally collected seeds for my container grown population.  I think I’ve repaid that loan of a few seeds with adequate interest.

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