strawberry raspberry hybrid plants

It is time for another update on my strawberry raspberry hybrid. The plant still looks like a strawberry plant. While I took every precaution to prevent stray pollen I can’t ever be truly certain it is a hybrid unless it is independently tested by a lab, I will provide an update on that later in this post.

While the strawberry parent grows runners from a few months old this plant has never produced any runners.  I unsuccessfully attempted to divide the crown in early spring, for a while it looked promising has since died.  Unfortunately this means that all my eggs are in one basket.  I find this rather stressful.  I do have some other plants, but I really like this first one.

Note the greatly elongated petiolules and bumpy berry

The plant itself is still producing flowers that are subtended by a leaf, and they often have extra petals.  It is still producing leaves which usually have greatly elongated petiolules and the leaflets are sometimes oddly shaped.

It fruited a few weeks earlier in spring than the strawberry parent, and it produces more flower stalks and more flowers per stalk than the strawberry parent, making it a productive plant.  The strawberry parent produces up to 8 flowers per stalk with 5 to 6 being average while the hybrid is averaging 10 flowers per stalk.

Lumpy hybrid berry

The first few berries produced in spring tasted horrible, very sour, and not fragrant.  The first berries also looked different to last year, they were rounder and had very deeply set achenes.  As the season has progressed they started getting longer and tasting better much nicer like the previous year.  Most of the berries have all of the achenes on the outside just like a strawberry.

Three of the berries had achenes on the outside like a strawberry but also contained a small number of seeds internally within the flesh like a raspberry.  I am not sure why this was happening, it may be a genetic thing or may be a result of insect damage?  I have not taken a photo of this as it happens so infrequently.

In spring the plant was considerably larger than any of the parent strawberry species.  The petioles are much longer and thicker, while the leaflets are considerably longer and wider.  Petiolules are virtually absent in the parent species, but are often elongated in this hybrid.  Leaf size varies with the season so I try to compare it to the strawberry parent, and so far it is much larger.  I had a lot of plants of the parent species, and none of them was even close in size to the hybrid. 

The berries are white inside

I collected seed from the hybrid as well as from the parent strawberry.  It was not until I had two little bags of seed side by side that I noticed the hybrid achenes are larger than the strawberry achenes.  They weren’t all larger, some were the same size, but on average they were noticeably larger.

I had started to wonder if perhaps this plant was not a hybrid but was a result of spontaneous polyploidy.  Polyploidy can cause larger leaves and fruit, it can cause more vigorous growth and more flowering, it can cause odd flower structures and other morphological abnormalities, often polyploids taste comparatively insipid but sometimes they can taste good, and it could explain all of the difference I have seen.  I wanted to see if it was polyploid.  I took a sample of pollen from this plant as well as both parent species and observed them under a microscope.  Polyploid pollen is often larger than diploid pollen.  Surprisingly they were indistinguishable and none of the pollen was noticeably different.

I emasculated and bagged some flowers and attempted to pollinate them by hand.  I missed blackberry season last year and attempted to pollinate some with youngberry pollen and others with raspberry pollen.  Flowers that were not pollinated or were pollinated with youngberry aborted early, indicating that fruit set is caused by effective pollination and not through apomixis.

I want to try youngberry pollen or any of the blackberry aggregate this year as I have a feeling it may be possible.  Some of the raspberry pollinated flowers aborted late, and some appear to have been successful and were forming fruit until they were eaten by something in my garden.  If these were a hybrid then these seeds would carry three quarter raspberry genes and I would love to have seen what the resultant seedlings looked like.

Most have weird bumps and lumps for some reason

So far, everything indicates that this probably is a true intergeneric strawberry raspberry hybrid, but I can’t be certain.  I contacted a lab to get this plant tested to determine if it is a true hybrid.

After several attempts and being told that my request had been passed on and must have fallen through the cracks the lab eventually replied.  They said this specific testing has never been conducted, but it may be possible. They also warned me that as this type of analysis has not previously been performed it is unknown if there will be enough variation between the parental strains to determine if the hybrid is a true hybrid.  A brief literature search indicates that both parent species have been extensively studied, meaning that there is a high chance of this test being conclusive.

I provided them with further details, twice, and am still waiting for them to reply with pricing and further details.  Hopefully this is within budget and they are able to conclusively determine if this is a hybrid or just an interesting mutant strawberry.  I have no idea what a test like this would cost but I really want to know for sure if this is a mutant or is the first ever fruiting strawberry raspberry hybrid.  Who knows, I may turn to some form of crowd funding in order to cover the cost.

Below are some pictures of the berries, most have weird bumps or lumps, a small number look like the strawberry parent.  I have some other exciting news about strawberry raspberry hybrids, but that will wait for another blog post.

Edit to add: I sent samples of these plants to the CSIRO who tested them and determined that they are true intergeneric strawberry raspberry hybrids.  The results can be seen here.