Can you cross any of the domesticated brassicas with cardamine hirsuta/hairy bittercress or alliaria petiolata/garlic mustard?
I’ve got hairy bittercress or a lookalike flowering right next to turnips and cabbage that are about to flower. Actually pinched some of the flowers off of the short-lived bittercress to allow for more overlap.
I would rather try this experiment with something better behaved (and ideally native) than garlic mustard but am not yet ruling it out.
I’m interested in this topic too. I am growing several wild and feral brassicas.
I think this open access article could be of use. I have only done an hour dive into the literature, and I have a feeling there are other useful references still to be found.
Interspecific Hybridization for Brassica Crop Improvement
Authors: Elvis Katche, Daniela Quezada-Martinez, Elizabeth Ihien Katche, Paula Vasquez-Teuber, Annaliese S. Mason
PDF link: https://cbgg.hapres.com/UpLoad/PdfFile/CBGG_1055.pdf
Interspecific hybridization is widespread in nature, where it can lead to either the production of new species or to the introgression of useful adaptive traits between species. In agricultural systems, there is also
great potential to take advantage of this process for targeted crop improvement. In the Brassica genus, several crop species share close relationships: rapeseed (Brassica napus) is an ancestral hybrid between turnip (B. rapa) and cabbage (B. oleracea), and mustard species B. juncea, B. carinata and B. nigra share genomes in common. This close relationship, plus the abundance of wild relatives and minor crop species in the wider Brassiceae tribe which readily hybridize with the Brassica crop species, makes this genus an interesting example of the use of interspecific hybridization for crop improvement.
In this review we introduce the Brassica crop species and their wild relatives, barriers to interspecific and intergeneric hybridization and methods to overcome them, summarize previous successful and unsuccessful attempts at the use of interspecific hybridization for crop improvement in Brassica, and provide information about resources available to breeders wishing to take advantage of this method in the Brassica genus.
Guide to the wild germplasm of Brassica and allied crops (1993)
Center for Land and Biological Resources Research (Canada)
Authos: Warwick, S. I; Francis, A
Part 1: Taxonomy and genome status in the tribe Brassiceae (Cruciferae)
Part 2: Chromosome numbers in the tribe Brassiceae (Cruciferae)
Part 3: Interspecific and intergeneric hybridization in the tribe Brassiceae (Cruciferae).
Part 4: Wild species in the tribe Brassiceae (Cruciferae) as sources of agronomic traits.
Part 5: Life history and geographical data for wild species in the tribe Brassiceae (Cruciferae).
I thought I might share images of the brassicas in my ‘wild and feral’ beds which are currently flowering in late March in USDA Zone 6b Kentucky. I also had cultivated wasabi and broccoli nearby, but they have succumbed to deer pressure and weather.
Species that I am at least somewhat confident are a part of my garden overall, either in this location or within a quarter mile:
One of these photos portrays a cress-leaved plant that I am having a hard time proving to myself is not a member of the Senecio genus. Having nibbled on it I do think it’s almost certainly a brassica, I’m hoping ‘‘Erucastrum nasturtiifolium’’ but keeping an eye on it through the lifecycle before I draw more conclusions or eat much of it.
Fantastic! I love this 
. I’ll look forward to perusing the articles time permitting.
I was already deeply interested in wild plants before catching landrace fever, and hearing about Joseph and Mark’s success with teosinte and corn clearly illustrated to me some of the value that can come from a fresh influx of wild genes. The perennial sorghum available at Adaptive Seeds/EFN, purportedly descended from a sorghum/johnson grass hybrid, reinforced this for me.
I may very well try to manually pollinate and mark certain flowers of both parents. Not something I have experience with, but I won’t learn without trying. I probably should mark them since I can’t keep it all in my head
If this works and a resulting hybrid is viable, I would be okay if it takes a few years to backcross to a market-ready phenotype. This would probably mean more vigilance with “weed” control than we usually exercise but that’s OK. I am not a market gardner and I see enormous value in wild parentage. And because both parents are perfectly edible already, I have few concerns about the potential fallout of succeeding at a cross.
edit: On the CMS side I’m already needing to screen a number of specific brassicas about to flower for fertile male parts because they are transplants, some of more reputable provenance than others. I am growing at a small enough scale and am out among the brassicas often enough that this is feasible
Well I guess I had time 
Skimmed these over. Interesting read and some great background info!
I didn’t see any clear indicator of ploidy for hairy bittercress or compatibility with oleracea (if there is I missed it) so I’ll stick to the original plan of letting the plants decide 
One immediately actionable takeaway for me was that post-fertilization issues can easily tank an interspecific cross and some means to mitigate that. I’m not about to do anything in vitro and I certainly have no intention, means, or interest in gene editing. But I can totally attempt pollination on unopened buds which I did today with a hairy bittercress father and cabbage mother whose flowers hadn’t yet opened.
I just plucked an opened bittercress flower with visible pollen and rubbed it on the nearly open cabbage buds. If it’s meant to be more invasive like bean pollination I will need to watch some videos 
A ‘karyotype database’ akin to Wikipedia with ploidy and other chromosome information would be so useful!
@H.B it seems like ‘Cardamine hirsuita’ is 2n = 16: Source 1 Source 2
I will try to add this information to its Wikipedia article. One small step…
So 2n 16 and 18 like nigra x oleracea? 
I thought this passage I bolded, from the older paper “Chromosome Study as an Aid in Tracing the
Evolution in Cruciferae” was thought-provoking:
The somatic number of several species of the tribe Brassiceae show a varying range from 2n=16, 18, 20, 24 to 36. On the basis of their gross morphological character, a number of chromosomes seem to be common to all of them. A critical analysis shows that they differ from one another in minor alterations in the representatives of the types and the different combinations of these types as well.
Edit:
So 2n 16 and 18 like nigra x oleracea?
The way I read this, yes like Brassica nigra. I haven’t seen the chromosome count for the cross with oleracea.
It turns out I have some Brassica nigra x B. oleracea seed from a recent impulse buy at the hardware store. I will be sowing these seeds in the bed previously portrayed 
Awesome!! 
The salad turnips are flowering (and more brassicas quickly on the way). The hairy bittercress is a common weed on our place, so almost all if not all the domestic brassicas have some close enough to make a difference if they coflower. I have taken steps to encourage this.
Biggest hairy bittercress I have ever seen (I usually see them quite small). On the left. This one is included just for fun - - it is too far away from the turnips and cabbages to be a likely pollen donor or receiver.
Wanted to include a link to this very relevant post:
Brassica dilemma - will black radish and arugula cross?
Raphanus Raphanistrum × Cardamine Hirsuta
This year I have what look to be several spontaneous intergeneric hybrids between radish and hairy bittercress. There is nothing particularly noteworthy about it at this point other than its existence.
The plants look like very large hairy bittercresses with larger leaves, taproot, and dramatically larger, radish-like flowers when open.
They are flowering along with turnips and soon kohlrabi and napa cabbage. I have begun weeding nearby cardamine hirsuta, as a backcross in this direction doesn’t seem like the best potentially possible step forward
Very interesting observation. Sounds like your plan to nudge it toward back crossing to the more domestic parent is wise. Pollinating among themselves could also be useful. Do you think you might have enough seed in coming seasons to share? Not for me, but these rare chance hybrids are worth spreading to see if other people can help them progress to becoming useful new crops.
I hope so! I’m excited about this but also feeling a little out of my depth today. Cardamine Hirsuta is an ubiquitous weed at our place so unless I apply more control than I have time for I can’t prevent backcrossing in the “wrong” direction. The open flowers are naturally getting F1, turnip, and hirsuta pollen. Pollen production seems prolific so I could consider storing it until GTS and other radishes begin flowering.
These plants overwintered as itty bitty seedlings and grew a little through the winter, so that is one potentially nice trait to think about bringing into, say, daikon (my best current guess as to the father). At the same time I think cold hardy radishes are perhaps not that uncommon?
If the pods are good to eat that’s another possible benefit - - hirsuta seems to have a snappy lifecycle. It also will spring up right in the middle of a dense grass stand without issue.
Other than that the greens taste very mustardy to me and the only root I’ve observed so far is tiny compared to radish.
