Tim, these were propagated by TC. There are some excellent videos on YouTube, you could spend days researching the TC subject!
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You can definitely propagate Yuccas this way. Like Canadianplant said, it has to be done in a sterile environment.
TC is something that I'd like to get into, but if I did, I'd probably want to spend $10k on equipment and devote an entire room to it (to have the amount of plants that I'd want
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). You can practice TC at home as well, and again, there's lots of info about home TC on the internet.
Jesse, these orchids were grown from tiny plantlets (cuttings). I can tell after seeing obvious divisions, where lots of new stems were prompted to grow. Orchid seeds need a specific set of nutrients and sterile conditions to germinate, and an agar TC solution is the way to go.