6

I'm trying to pick out the best plants to attract birds to my yard, and have become very interested in serviceberry trees for this purpose. Should I avoid the hybrid varieties of this species (such as Amelanchier × grandiflora) in favor of versions like A. canadensis which birds and insects may be more familiar with? Or does that not matter, since both "parents" of the hybrid are also native species to my area? Does this apply more generally when selecting native plants to build a better wildlife habitat?

1
  • Very interesting! I too would like to learn more as well :) Apr 7, 2021 at 21:13

3 Answers 3

4

Amelanchier × grandiflora is an example of a "nativar," that is, a cultivated variety of a native plant.

While there's some range of opinions, reputable sources agree that it's best to plant the native species (eg, A. canadensis) if you can get them. If you can't get native species, nativars are at least better than non-native plants.

If you do have to plant a nativar, at least make sure it's not sterile. Beware of varieties that advertise "double flowers." Double flowers are usually sterile because they make extra petals instead of the pollen- and seed-producing parts. (Amelanchier × grandiflora does make non-sterile flowers, so it's better than some nativars.)

Further reading:

2
  • This is a stupendous and detailed answer. Thank you so much! Apr 16, 2021 at 22:41
  • The sterility of a hybrid is I think a less serious problem than some of the other problems that I bring up in my answer. Also, some sterile hybrids are widely naturally occurring, such as Circaea x sterilis. I am more concerned with either weakening (through outbreeding depression or maladaptive characteristics) or strengthening (through new genetic material) the population genetics of local plants, in ways that can create serious problems. I recommend only using locally-occurring natural hybrids. I think cultivars in general are more harmful than hybrids alone.
    – cazort
    Oct 19, 2021 at 15:58
3

While this is a natural question to ask, there is no one-size-fits-all answer to this question: it depends on the particular hybrid.

Naturally-occurring Hybrids

Some hybrids are naturally occurring and even fertile. For example, in the Mid-Atlantic, the hybrid oak Quercus x heterophylla, which is a cross of willow oak (Q. phellos) and northern red oak (Q. rubra) is found in most counties from southeastern PA and northern DE, east through much of NJ. Not only are both parent species native in this region, but the hybrid itself is. Another, even more widespread native and naturally-occurring hybrid is Apocynum x floribundum, or "intermediate dogbane", a hybrid of the two native dogbane species.

There is no reason to avoid most such hybrids, but in some cases, they can be sterile. For example, the hybrid enchanter's nightshade Circaea x sterilis, although relatively widepread in the wild, cannot reproduce by seed, so it represents a genetic "dead end". If you wish to contribute genetic diversity to local populations of one of the parent species, you need to plant one of the parents. On the other hand, some gardeners might actively want sterile species, as they will only reproduce vegetatively and not by seed.

Unnatural Hybrids of Native Species

Amelanchier x grandiflora is a slightly different example. Its parents are both native, but it does not occur in the wild. There might be some ecological consequences for planting such hybrids, but in general I think such hybrids are likely to cause less damage than a hybrid that contains non-native parents.

Hybrids with one or more non-native parents

The worst-case would be a hybrid containing one or more non-native parents. An example of this would be Quercus ×bimundorum which is a hybrid of English Oak (Q. robur), native to Europe, and white oak (Q. alba), native to North America. There is potentially more harm that could come from such hybrids, the worst case being introducing new genetics that cause a plant to become invasive. Examples of this phenomenon occurring would be the invasiveness of mulberry (Morus) hybrids between the introduced white mulberry and the native red mulberry in North America, and a second example of this phenomenon occurring in the same species would be the common reed, Phragmites australis. Anyone who has worked trying to control either of these plants will testify to the importance of avoiding the introduction of new genetic material through hybrids.

Cultivars that are also hybrids

It is also, however, worth considering not just whether the plant is a hybrid but also whether or not it is a cultivar. Cultivars are specific, named varieties of plants, usually developed by the nursery industry, but some of them are simply wild plants that were selected for desireable properties and then propagated.

Cultivars can have less ecological value in a long list of ways. Cultivars lack genetic diversity: in most cases all individuals of the cultivar are clones. In many cases, selective breeding has modified the plant in such a way that makes it less adapted to survival in the wild, or modified it in such a way that makes it less attractive to the insects or other animals that depend on it (such as being bred for insect resistance, or a flower structure that may look pretty to humans but pollinators cannot access.) There is also a risk of outbreeding depression and/or maladaptive characteristics for local conditions when using cultivars derived from distant populations. And lastly, there is the risk of creating new problem populations of weedy plants by introducing new genetic material into local plant populations.

Which of these problems, if any, varies based on the cultivar, but if you don't know the answer to these questions, and don't want to put in the time to researching the particular cultivar in question, best practice is to avoid all cultivars.

Does this all seem like a lot of information, perhaps more than you want to think about? Then stick to using wild-type, naturally-occuring hybrids or straight species.

In Summary

For a quick-and-dirty answer on best practices, I would say that it is best to only plant hybrids if they are hybrids that occur naturally in the wild in your area, and then, ideally plant one that either occurred naturally in the wild or was propagated from such a plant, not one that was bred in a nursery.

If you can't find these, just stick to straight species (not cultivars) of locally native plants.

I find the best place to look up the range maps in fine detail (to county level) is BONAP. BONAP lists naturally-occurring hybrids. Hybrids are probably under-reported so you're probably fine planting a hybrid a few counties over but I still think pure species are the better choice, especially when the hybrids are sterile.

2

Though this answer doesn't supplant the great and detailed ones that were given when I first asked the question, I recently came across a source which addresses the precise nativar cross I was looking into:

https://www.ecobeneficial.com/ask_ecobeneficial/is-autumn-brilliance-serviceberry-a-good-pollinator-bird-plant/

Turns out that in my particular case, Autumn Brilliance is still beloved by birds (and produces tasty fruit for humans, too). The article also illustrates some of the perils of nativars more generally, though - such as the lower genetic diversity you get compared to the straight species.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.