Sunday, August 25, 2013

Collecting Obesa Seed

Euphorbia  obesa   -   Collecting Seed

If you have a male and female plant of
Euphorbia obesa in flower at the same time there's a good chance the flowers on your female plant will be pollinated and set fruit.  The fruit is a small rounded capsule holding three seeds.  A modest sized plant, such as the one at the right, usually produces six to ten fruits and thus 18 to 30 seeds.  However, there's a difference between the female producing seeds and your chances of harvesting them.
 
As the fruit of E. obesa dries, pressure builds up along the seams, and when one of these seams splits, the seed is propelled outward with substantial force.  The force is great enough to propel the seed up to ten feet (3 meters) away from the plant.  If you do not have some type of mechanism in place to collect the flying seeds, or prevent them from being propelled, you will lose most, if not all of the seeds.
 


The plant at the right has propelled most of its seed.  There is only one fruit with seed remaining.   There are a number of tricks use to prevent the fruit from splitting and throwing off the seed.  One is to put a dab of glue on the side of the fruit.  This will prevent the fruit from splitting with force and hold the seed in a partially split fruit or allow the seed to drop into the pot.  A piece of tape is sometimes used around the fruit to accomplish the same thing.
 

Another method of getting the seed, is to collect it after it has been expelled from the fruit.  Some growers cover the top of the plant with a piece of mesh or nylon, (like a hat covering the fruit)  to trap the seed when it is propelled.  The catching material is secured around the plant with a rubber band or string.  I have a number of plant and I prefer to use a large trap (seen at right).  I use a plastic crate that is lined inside with window screen.  The plants with fruit are placed inside and the crate covered with another piece of screening.  As the seeds are propelled from the fruits, they are trapped within the screened crate.  Some seed will fall into the pots but 80 percent usually ends up on the bottom of the screened crate.  I can collect hundreds of seeds with this method with very little work on my part, save making the trap crate.  The screen allows air and light (although there is about a 20 light reduction due to the screen) to get to the plants and I keep the plants dry during this seed collection period. 

Of course you still need the basics, flowering females plants to produce the fruit and seed, and at least one male plant in flower at the same time for pollination.  I have never had to take a hand in the pollination.  My plants are outside and ants seem to do most, if not all, of the pollinating.  Strangely however, I have also had flowering plants set fruit inside the house, and I never saw a single ant.  I have no explanation for how this pollination occurred....invisible ants....or poor grower eyesight.   




6 comments:

  1. Beautiful obesas :)
    I like your plants!
    Maybe the wind of an opened window did the job of the invisible ants?!

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    1. Thank you. I like obesas. A Euphorbia obesa was one of the first succulents I tried to grow. It was a female bought at a garden show and it lasted about 2 years before turning to mush. I bought three more obesas, and all turned out to be female. I put an announcement in my local C&S society newsletter asking if anyone had a male I could borrow for the summer. Someone did, and I borrowed it, and then I was in the obesa seed production business. :)

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  2. You have a lot of Euphorbia obesa! I have seen people use cotton wool over the seed pods to collect the seed. Do ants pollinate in the wild?

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  3. Yes, a lot. I'm not sure how many because I have a lot of small ones. I took 25 3 cm diameter obesas to the recent Washington DC C&S Society show and sale and sold them all.

    Cotton wool is a neat idea. Do you know how they hold it in place? I have no idea of how E. obesa is pollinated in nature. There's a nice article about the globose euphorbias, including E. obesa, in the Euphorbia Journal No. 1, but no info in the article on natural pollinators. It's ants here in Maryland.

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  4. Great post! It's very interesting to see the fruits of Euphorbia obesa and how you collect the seeds, especially since I have never seen this before.
    Thanks!

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    1. Thanks Petra. I've been growing Euphorbia obesa for a number of years. They are generally easy to grow from seed. I collect several hundred seeds a year and usually give away or sell most of them. It's an attractive and neat looking plant.

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