Russian and Siberian kale are both B. napus. It is the same species as rape/canola and also rutabagas (though they are all different ssp., or at least varieties, I'm not sure). European kale, like your curly leaved and Tuscan, is B. oleracea. There are different cultivar groups of B. oleracea such as the gongylodes (kohlrabi) and acephala (kale and collards).

Mizuna is B. rapa, that is correct. Although there is also a different species that is called mizuna, I don't think that's one your referring to. Being that turnip and mizuna are both the same species, crossing would be no problem. The only real difference is that, for example, at the root shape locus one has a gene that tells it to make a turnip root and the other does not, similar to eye color in humans (I may have a "brown" gene at the eye color locus and my wife a "blue", but we are still able create fertile offspring as we are both H. sapiens).

I think that in the Brassica genus, even interspecific crossing is readily achieved and it has ben reported that rape/rutabaga/Russian kale was created this way (likely by accident) in the way, way back days.

I can't help you with the mustard question though, I don't have a clue on that one. I guess you could always coffee filter or paper towel a few mustard seeds you buy in the spice isle?

There are definitely going to be differences between the species of Brassica. I'm not sure they are really that apparent. Most genes have no effect on the phenotypes we can actually see with the naked eye. Those that do effect the appearence of the plant are highly variable within the same species (such as our mizuna vs. turnip example). With the amount of variety in the different cultivars I don't think morphology is the easiest way to discern the different species. I could be wrong and if someone from the Botany forum wanders over here they'll probably tell you I need to revisit biology 101 haha.

This post was edited by ZachS on Fri, Jan 24, 14 at 15:37

Zach, I just wanted to say thank you for the help.
-Eric

This is interesting because Seed to Seed is not real thorough on some of the brassicas and she does list Siberian and all other kales as two different species. I am preparing a seed saving class and want to be able to say if broccoli rabe, tatsoi, baby bok choy, etc. will cross or not. Here in MN many brassicas are not winter hardy and not worth explaining how to save to beginners.

Pinetree has 3 mustard seed varieties and a mustard making kit.

Here is a link that might be useful: Pinetree

To follow up on my post from last year, I did get some "whole yellow mustard seed" (sold for culinary use, not seed) to germinate. The package I got even identified the Latin name (Sinapis alba), hopefully correctly. I'm assuming, therefore, that I can grow it for seed (to grind and eat as well as to plant) along with saving seed for mustard greens. I did actually grow and harvest a little of the yellow mustard seed last year. I may have planted it a little late and in a not-so-great location, but I got a promising amount of seed for the number of plants/amount of space anyway. I'm trying to figure out now when the optimal planting time would be. I probably should have gotten an overwinter trial started last September, but I didn't get around to that until late October. I haven't checked since this most recent cold (the coldest we've had all winter), but the mustard seed plants seem to have made it at least up until recently, so maybe overwintering will be the way to go here. The plants are just awfully small due to the late planting date. I intend to plant a larger planting as soon as I can direct seed late this winter/early spring, and perhaps that's the better timing anyways.

wiki : White mustard (Sinapis alba) is an annual plant of the family Brassicaceae. It is sometimes also referred to as Brassica alba or B. hirta.

I read an article by a university that dealt in breeding canola/rape seed for oil - they said that napus and B. oleracea and even rapa were all very closely related and crossed easily. it is driving me crazy because we all eat so many brassicas. Even radishes are a type of brassica. It is gonna be hard to save pure seed ! Thankfully the flower beds and flowering stems taste good so can be eaten when you are trying to time seed saving/poliination.