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Does anyone know of any sites that show how to cross fertilize opuntia?
Specifically, I have a lot of humifusa and some phaecantha that I would like to cross pollinate.

Get a soft paintbrush, wiggle the stamens with the bristles of the brush to rub some pollen off onto the brush, then brush the pollen off onto the stigma of another. Simple!

Do these two species flower at the same time of year, though?

They overlap a little bit, but usually it's at different times. I thought the bees might have already done that for me, but I won't know until the seedlings from the last batch get larger.
I thought it was more complex, that you had to remove the stamens of the ones you wanted to pollinate so they wouldn't self fertilize. No?
If I save the pollen from the earlier blooming plants I could still just do as you said?

mjazz wrote:I thought it was more complex, that you had to remove the stamens of the ones you wanted to pollinate so they wouldn't self fertilize. No?
If I save the pollen from the earlier blooming plants I could still just do as you said?

As far as I know, that's how pollination works for most flowering plants including cacti. You don't have to remove any of the sexual organs to induce fruit formation. It's only with certain plants such as some Orchids where you might have to remove the stamens in order to produce seeds, but not in cacti. However, it might be easier to just break off the stamens and store them as they are larger and easier to work with than just raw pollen.

And yes, I believe you can store pollen. Pollen is just a protein, so you'd store it in the same manner as other proteins in order to keep the pollen active:
Cold and dry. The method i've seen is to collect the pollen and brush it off into a small plastic baggie and then place it in a freezer. Be sure to label things, though.

It may be a little more complicated than that simply because you have O. phaeacantha. That species (and some other hexploids) are known to produce viable seeds without pollination so if you get seeds they may not actually be hybrids. O. humifusa may be tetraploid and O. phaecantha is hexaploid so hybrids would likely be somewhat sterile pentaploids. That woudn't matter much if you just want to produce a nice flower and rapdily growing plants.
Dean

I didn't get a chance to try it this year, thanks for the answers, though. The plants look so radically different (for opuntia) that I wondered if cross pollinating them would work. The humifusa have a sprawling habit, which isn't as attractive, to me, but they easily tolerate the freezing rain we sometimes get instead of snow in R.I. I was hoping that advantage might be inherited.
It would be interesting to see what the results would be, if any. You could always clone them. The "rapidly growing" part sounds good, too.