Dr Darren Abbey: A few years back I made a hybrid between these two bean varieties. My blue bush-bean is at right and Wit-rood boontje (Dutch: "White-red bean") on the left.

A few years back I made a hybrid between these two bean varieties. My blue bush-bean is at right and Wit-rood boontje (Dutch: "White-red bean") on the left.

The hybrid (F1) between the two produced dark-purple seeds that eventually dried down to black.

Last year I grew out the F2 generation. In previous bean experiments I've found that the bulk weight of the different bean classes was a good proxy for the number of plants in each category, so I can calculate ratios without having a trellis for each plant.

The masses of the categories: Black = 391 g White = 163 g Brown = 52 g Blue = 55 g Total = 660 g

The first thing that stands out... White (162g) / total (660g) = 24.55% I knew white was a recessive trait from the F1 being black, but it's nice to see an almost perfect Mendellian ratio. (The expected ratio for a recessive trait is 25%.)

There's a few more colors at play, so once we rule out the white seeds... Black (391g) / total-non-white (498g) = 78.51% The expected ratio for a single dominant trait is 75%. That's a pretty good match too.

We're left with brown and blue seeds, totalling at 107g. Blue (55g) / 107g = 51.40% Brown (52g) / 107g = 48.60% These numbers do not reflect a simple Mendellian ratio.

I like the blue ones

They took a few years to make. You can order similar ones from a few places.

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