Some plant species, such as Mimosa pudica, have hard-shelled seeds. I have tried to plant them from seeds a few times in my life, in Hong Kong.

I know that what follows is just an anecdote, but I hope it illustrates my point.

The first time I tried to plant M. pudica, I simply dumped the seeds in moist soil, in summer. They didn't germinate. So my grandma told me that I have to soak the seeds in boiling hot water. I didn't believe her at first, but my first batch didn't germinate so I thought I might as well try. So I put a second batch of seeds in a glass and dumped scorching hot water on them. Lo and behold, a few days later, this second batch started germinating.

Why is it that when planting these plants artificially, we have to use hot water? How would they manage to grow in the wild? (I do see them in the wild.) The soil temperature in Hong Kong is nowhere past 40 degrees Celsius, even in summer, according to the estimates in this article: https://doi.org/10.1016/j.enbuild.2011.09.026

What am I missing?



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