Fern Sex


So, we are talking about plant reproduction already a bit on this nature walk, and I see little black dots on the undersides of some of the fern fronds. It reminds me that a few weeks ago, a fern frond kept poking Arthur in the back of the head as we sat in an outdoor coffee shop. He noticed the black dots and didn't know what they were. I pulled the wood fern from the previous drawing (Dryopteris sp.) under a dissecting microscope, and here's what I saw on it's underside…

The dots themselves are each called a sorus, and that's about all I could see with just my eyes. With magnification though, they look like little grey rounded fortune cookies with golden, brownish spheres spilling out of them which are the sporangium. I also see little white dots on the leaves, they are very tiny and those are the actual spores.  Fern spores are haploid, and fern reproduction is not entirely linear, so we'll leave it at that.

(Unless, you're Really curious… in which case I found a reasonably good diagram of fern reproduction on the University of Maryland's website: http://www.life.umd.edu/cbmg/faculty/acaines/bsci124/AlgaeSpore.html)

UC Santa Cruz, Natural Reserve/Natural History Museum

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