Easy analogy:
Cross and horse with a donkey, a mule
Mules cannot reproduce
Some hybrids are 'mules'
Mr. MegA

Mr. Meg, you explained that beautifully. How would you explain it better for 12 yr old boys, I had to do this in front of 60, I was careful with every word that came out of my mouth, the teacher gave me a thumbs up to go ahead with the lesson.
I didn't know that people were standing behind me until I heard them giggle. Many plants are self infertile. I was grooming an Echinopsis and one of the boys asked why I was cutting of the flower, the fruit was full of seed, white and not fertilized. Then I pollinated the yellow flower with another that was red and that darn kid asked why I was doing that, he was the only one that caught on what I was doing. He he he The teacher thanked me and said that I was making his life biology lesson he was planning for the next week easier. Norma

Norma- From you a high compliment. Thank you.

Sorry about the typo's. Posted from a hand held.
Loved your story! ROFL!
12 Y.Os. Not yet adults, no longer kids.
You have nerves of steele.

Happy New Year to you and to all
Mr Mega