Brassica dilemma - will black radish and arugula cross?

Brassicas. I love them! But i didn’t know Arugula or rocket salad flowers in spring… At least this very nice tasting variety does. It has big juicy leaves.
I am used to the rough small leaved wild variety i have grown for five years. It behaves like a perennial. It stretches itself with long branches and grows a little colony of leaves a bit further from the motherplant. I mix them in my salades. Great, bit rough smallish leaves though. Not very civilized maybe.
But it flowers in autumn, survives the winter and starts again! I like that trait.
I thought to mix the two and see what happens.
Maybe i’ll be able to push this variety toward a big and soft leaved perennial.

I would like to try at least. We have all this luxury, time, knowledge and the interwebz with loads of crazed seedsaving landracers to chime in and create even bigger confusion. Or clear things up once and for all.

So i made a mistake. Next to the line of arugula i have seeded a line of black radish. And they’ve both started to come into seed now.
The black radish is a Brassica of the genus Raphanus. The Arugula is a Brassica of the genus Eruca. Will they cross freely?
I want to be able to have a lot of Black Radish seed to use as a cover crop. Or maybe start a landrace with them. In both cases saving as many seeds as possible would be a good thing… But how? Without compliczting things…

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Is it theoretically possible that they will cross? Yes. Do bees love brassica flowers in general and arugula in particular, further increasing the possibility? Yes. Have I ever had an apparent hybrid in my self-sowing arugula patch that is 10 feet from all sorts of brassicas (mostly broccoli, Chinese broccoli, and rapini) that are blooming? No. But I did have a volunteer pepper show up this year. Joseph’s book discusses the actual likelihood of a cross between two patches that are close enough to theoretically be a risk being fairly low. My anecdotal evidence concurs. I wouldn’t sweat it. Worst case scenario is you get a few hybrids that you don’t like and pull them before they go to seed.



I can’t find where I found this image but I saved this from a thread somewhere.


That’s really interesting. Here’s a link that looks like the original paper.

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Thank you so much for that PDF!!
That’s a treasure.
It contains handpollinated percentages of the most likely crosses.

There are many varieties of Eruca sativa that will freely cross with each other. They vary by leaf shape, stem color, and spiciness as far as I know. The perennial rocket is Diplotaxis tenuifolia, which has yellow blooms later in the season. It does not cross with the rocket (Eruca sativa) that flowers in the spring. I don’t think the black radishes will cross with the rocket, but they cross freely with other radish varieties.

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Might it cross if you could get them to grow at the same time?

Lauren, I have grown both Eruca sativa (rocket) and Diplotaxis tenuifolia (wild rocket) in the same garden for many seasons, and I keep honeybees that like both species. I have never noticed anything in my garden that looks like a cross between the two. Diplotaxis tenuifolia blooms for a pretty long time, but I’ve never noted whether it’s blooming when Eruca sativa is blooming. I think it might be possible for both plants to bloom in the fall - if Eruca sativa is planted in the spring - it will bloom in summer or fall. I have overwintered Eruca sativa blooming right now, and the Diplotaxis tenuifolia is not blooming or actually doing much right now.

You are correct Jenna, it’s the Diplotaxis Tenuipholia. And it doesn’t hybridize according to Wikipedia either which does confirm your observations! That’s good to know.

I’m not trying to create a radish landrace. The Black Radish i grow i’d like to incorporate in a winter covercrop mix. It’s root will leave a place in thé soil after dying off which can easily be colonized by other deeper rooting plants. Hopefully it can function as an aearating/break up crew in combination with Parsnip and Purple Salsifies.

But i’ll definitely slowly landrace those. Adding new genetics as i come across them.

Same for the Arugulas. Good to know they will cross easily.

So you basicly have a Aragulas/Eruca landrace Jenna?


I guess I have an arugula (Eruca sativa) landrace - It self seeds where it wants, I haven’t selected for any traits, but when I attended a seed school someone said her mother selects for spiciness. I’m too lazy of a gardener to mess with the arugula. I live in the high desert of southwestern New Mexico, and I’m happy to have arugula pop up wherever it gets enough water to germinate. and to have bees that take care of the pollinating.



That sounds like an awesome landrace! Something that can self-seed and needs no care or breeding, because you like it just as it is, can be a delight in the garden.

I wonder if it would actually be a favorable cross? If you could get a plant that the leaves and the roots are both delicious, like beets!

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Kerrianne. It could well be that amazing cross, i doubt i’ll have time to notice though…but if i do, i’ll report back.

The Arugula is making seed pods.
The Black Radish is a bit behind.

It’s going well!

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