Strombocactus seed are really tiny

[promethean_spark]

For years I've been frustrated with my strombocacti, they flower reliably but always seemed to dry up without setting fruit like other cacti, the base of the flower would swell a tiny bit and then dry up within a couple weeks - never making what I'd consider a fruit.
This year I had three different plants open at the same time, visited them several times a day with my paintbrush and still the same results - very frustrating. A couple days ago I sowed strombo corrigidoriae, and was struck that the seed is very, very tiny. Popped off one of the dried flowers, saw it had opened a vertical slit at the base as described for fruit opening to release seed, and got some orange dust out of it where I would expect seeds to be, looked at it under a kids microscope, and it turned out I had hundreds of seeds. I guess they were doing their thing the whole time and I just was expecting something a bit more like the seed of other cacti since it had been many years since I planted them.

strombo_seed_resiszed.jpg (24.93 KiB) Viewed 2753 times

[jerrytheplater]

That really is tiny seed. I would have probably thrown it out, thinking no pollination.

[promethean_spark]

The proof will be in the pudding if they germinate... Could be aborted embryos, but they looked like the seeds in microscope photos online.

[Aeonium2003]

Pictures from a google search show that the seed is quite tiny...

[Hanazono]

Seeds of Strombocactus are tiny but they are not like dust.
The photo is my strombocactus seeds, just start germination.

[jerrytheplater]

Hanazono

I see you are germinating your seeds on top of a fiber, and not in contact with the potting mix. Would you please explain your technique and why you do it? Great photo by the way.

[7george]

Seeds of Strombocactus are tiny but they are not like dust.

I also think like Hanazono. That on first picture might be just some dust from some dried fruit pulp.
Here is my old photo of S. disciformis seeds.

Stromboseeds_50.JPG (112.92 KiB) Viewed 2721 times

This is from today.

[Hanazono]

G'morning Jerry,

I see you are germinating your seeds on top of a fiber, and not in contact with the potting mix. Would you please explain your technique and why you do it?

I bought seeds of Strombocactus several times but they never germinated. I was not sure the reason.
Seeds were mixed with dust but I could see actual seeds also.
Sice I bought seeds, I did not know the age of seeds. Seeds of Strombo cactus are tiny and so their lifes may be very shot.

My friend gave me two grafted flowering size Strombocactus and I harvested seeds by myself.

Seeds of strombocactus are tiny and they are sunk between grains of potting-mix. As the rsult you can not see the behavior of seed germination.

I set two types of pots. One is a normal and the other is as shown on the photo.
The fiber is a tissue paper. 2 thin sheets are used as a tissue paper in here. I stripped the tissue paper and used Just one sheet.

The germination of both two types was well. I could see the germination behavior by using the tissue paper.
Tissue paper was broken out and it did not affect following growth of seedlings.

I repotted 100 seedlings, 25 seedlins x 4 pots and lost some of them. They have grown very slowly.

Frank

[jerrytheplater]

Thank you Frank. That makes perfect sense, using tissue paper to support the seed to visually observe the germination. If you used a fine enough potting mix to support the seed, it would probably have very poor drainage. You said you got good germination using tissue paper and without it too. It seems the seedling roots were able to penetrate the tissue paper without any problem. I wondered about that when I recently started some Frailea seed on top of paper as an experiment to observe germination, but I did not intend to grow the seed out.

So now the question is, I wonder how the seeds get sown out in the wild where the plants are native? How do they make it from the dried ovary to the ground far enough away from the mother plant? I suppose wind could carry them as they are so fine.

[7george]

===
So now the question is, I wonder how the seeds get sown out in the wild where the plants are native? How do they make it from the dried ovary to the ground far enough away from the mother plant? I suppose wind could carry them as they are so fine.

You got it. It is the wind. These have the size of many mountain Parodia (also Blossfeldia) species growing on cliffs from where large seed would fall deep into gorges below and maybe never see the sun, that is my suggestion. Strombocactus also grows in cracks of step limestone cliffs.

[promethean_spark]

I saw a video of ants carrying around a strombocactus fruit. Maybe the seeds drop out as the ant carries it? They also float, so rain will wash them around and into cracks and crevices.

[promethean_spark]

I looked at them under a microscope, and they still looked like seeds, but maybe 1/5 as big as they're supposed to be. Maybe aborted seed?
Planted 80% of it and got 1 (one) seedling. Are there any tricks to improving seed set?