"American gooseberry" cultivars explained
I occasionally see people upload observations of "American gooseberry" hybrid cultivars which can't be identified to species due to the fact that the binomial species concept doesn't apply to these individuals. In order to avoid having to type out the same explanation every single time, I'm making this journal post that I can link people to instead.
Most of the information below was gleaned from the following really nice PDF I found, but I adapted it to have a greater emphasis on the taxonomy and floral morphologies.
https://www.uidaho.edu/-/media/uidaho-responsive/files/extension/county/bonner/horticulture/nifrc-gooseberry-varieties.pdf?la=en&rev=40460b120eed4993b43ded655c7b8cd1
Essentially, "European gooseberry" cultivars were developed in Europe, primarily England, and are derived from the species Ribes uva-crispa. (on a bit of a side note, I think the species concept for R. uva-crispa needs some serious rework, because it seems like an extremely lumpy assemblage of forms that are too geographically and morphologically distinct to be reasonably called the same thing, but we won't get into that today.)
Due to the long history of gooseberry cultivation in England, these cultivars are considered to have superior fruit size and quality. However, they are also highly susceptible to North American strains of powdery mildew (a fungal pathogen), which makes it very challenging to grow the European cultivars in North America. In order to circumvent this, "American gooseberry" cultivars were developed via crossbreeding the European cultivars with one or multiple closely related taxa native to North America. The two most commonly used species seem to have been R. hirtellum and R. missouriense, but it seems like others such as R. oxyacanthoides, R. rotundifolium, and R. divaricatum have also been used in more limited capacities.
Now, let's get into the interesting intermediate floral morphologies seen in these hybrid cultivars. First, let's look at a flower of the European gooseberry, R. uva-crispa s.s.:
Photo credit Daniel Cahen: https://www.inaturalist.org/observations/72819065
Pay attention to:
- The ovary with dense regular hairs, and sometimes (but not always) some glandular hairs
- The short, wide, densely pubescent floral tube
- The anthers which only slightly exceed the petals
- The short, greenish sepals with deep red tinting towards the face
Next, look at the flower of the North American Ribes missouriense:
Photo credit Jeffrey F Roylance: https://www.inaturalist.org/observations/11472719
Pay attention to:
- The completely glabrous ovary
- The long, thin, glabrous floral tube
- The anthers which significantly exceed the petals
- The long, white sepals with only moderate red tinting towards the face
Bringing it together, a flower of an "American gooseberry" cultivar, presumably the result of hybridization between the above two examples:
Photo credit Jeremy Atherton: https://www.inaturalist.org/observations/155541363
Note how the features are intermediate between the parents:
- The moderately pubescent ovary
- The medium-size, pubescent floral tube
- The anthers which moderately exceed the petals
- The medium, greenish-white sepals with some red tinting towards the face
In conclusion, we can see the breeding history of these American gooseberry cultivars reflected perfectly in their intermediate floral morphologies. Of course, there are probably other species in the mix, but their flowers are closer to this intermediate form so their influences are harder to tease out. The traits are not necessarily restricted to the flowers though: note how the branches in the photo of the American cultivar lack spines or prickles -- this is probably due to the influence of the often spineless R. hirtellum in its heritage. I do think that the extreme morphological differences in the flowers of R. uva-crispa and R. missouriense allow for a really cool and clear-cut case study in how hybridization can result in intermediate phenotypes.
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