[dmg]

I sowed 3 types of beans
Safari, green pod white oblong seeds
Maxi, green pod light brown oblong seeds
Mont d'Or yellow pod, black oval seeds
The writing on the label had washed off, but I was sure the harvested seed came from the mont d'or and is actually a darker brown and oval.
Could the mont d'or have been pollinate by 1 of the greens? I thought they were self fertilising with a small chance of crossing but I have literally hundreds of these seeds with only a handful of the original black oval.
Also the saved seed are almost twice the size compared to the packaged ones is this normal?

Thanks,
Dmg

[mumofstig]

Beans do get darker and smaller, as they get dryer through the winter. They may end up looking right 

[NickoV]

Beans do get darker and smaller, as they get dryer through the winter. They may end up looking right 

Yep, what mum says is my experience too.

French beans rarely cross in the UK because there is usually other more attractive nectare and pollen sources for the pollinators to feed on at the time of year the beans are flowering. I isolate ones I want to save seed from by growing them in a different part of the plot to other dwarf beans. Runner beans cross more readily because of their bigger flowers so I only grow one variety of those.
Also, even though the beans may have crossed, the seeds will be exactly the same as the parent plant.Any variation in appearance is due to growing condtions and state of dryness as Mum says. It is only when you plant those seeds and harvest the next generation of seed that you may see a difference in the seed coating as a sign of the variety crossing.Of course the plants will look different aswell if they have crossed.

Good practice is to always keep seed saved from different years labelled and stored apart, so if it does turn out that it has crossed, you know which batch it has come from.
Hang onto some of your original seed just incase this happens.

[mumofstig]

French beans self pollinate inside the flower, mostly before the flower even opens. Rarely they can be crosspollinated by insects.
As you say runner beans cross more easily

Runner bean flowers need to be 'tripped' by wind or insects before the beans set, and are much more likely to cross with other varieties grown nearby than french beans.   Ideally, to be sure that no crossing takes place, seed crops of runner bean should be at least 1/2 a mile away from any other varieties of runner bean.

http://www.realseeds.co.uk/seedsavinginfo.html

[NickoV]

Rarely cross pollinated by instects because their flowers are small and unattractive to our insects. In desert areas these same beans get more attention from instects because there is little other pollen and nectare around so there is up to a 25% crossing rate in these areas for these beans.

(According to Seed to Seed by Suzanne Ashworth)

Not relavent to us here though.