When my D. capensis first flowered, I had some trouble determining whether or not there were seeds in there. I found some "dust" in one of the dried up flowers, but assumed that couldn't have been seed, so I tossed it. I had trouble, too, finding a picture with a description of the seeds online anywhere to use in deciding whether or not I had seed.
SO. I just collected the seed of one of my flower stalks (anyone want a SASE for D. capensis 'Red' seed? ^.^) and decided I'd take a picture for anyone else having the trouble I did. For anyone to stumble across this:
The seeds are on a piece of graph paper with a 1/10" grid. Yes, the seeds are tiny. Much like dust. Based on their proportion to the 1/10 inch grid, they're about 1/40 of an inch long, or around 3/4 of a millimeter, somewhere in that ballpark.