Viburnums pollination, propagation, provenance: Oh my!

There have been many excellent discussions about viburnums here on DG's T&S forum. Some of them have a lot of good collateral info. I wanted to summarize my thoughts/opinions about the rationale of pollination in viburnums. Speaking of voluminous: stop now if you don't have your athletic reading shoes on and several cups of java; this is a marathon post.

Many posts on DG are hitting all around the concept of the conditions necessary for fine fruiting in viburnums. I'm looking to provide some clarification of what I think most people are looking for, information-wise. I use Viburnum dentatum (arrowwood) as the example, because it is a widely used plant that most folks have heard of and is easy to grow.

FIRST: there are some claims that the only reason that anyone says you need two different plants with viburnums is so that they can sell you something. Hogwash. University professors, researchers, and people on DG don't have a financial interest in your garden. You can send me money if you want; I'd rather see you post (by this fruiting season) that your viburnums are loaded with fruit because you installed several dissimilar individuals. And then you could send me some for my collection....

NEXT: Viburnums are monoecious, as has been stated elsewhere and can be looked up in texts. So are most of the Rosaceae family (Malus, Prunus, Pyrus, Amelanchier, Rosa, etc.) but many fruit tree growers will vouch for increased fruit production when multiple clones of a species are planted in proximity in order to provide cross-pollination opportunities. This implies (and researchers/scientists/someone besides me can verify better) SELF-INCOMPATIBILITY of individuals despite each plant having perfect flowers. This doesn't mean that a plant CANNOT pollinate itself, just that it does very little or poorly. There is anecdotal evidence (here on DG, and elsewhere) of some solitary plants of some species of viburnums that produce decent fruit crops, but it is so easy to plant a couple different ones that it defies logic not to. Co-opt a neighbor or some such if you don't personally have room.

NEXT: The biggest confusion I observe is the issue of species versus clone or cultivar. The best way to resolve this is to do a little reading in a biology or botany text, but I'll endeavor to layman-ize it. When someone says "I have the species Viburnum dentatum, not any clone" what they are saying is that they have an unnamed or unknown plant of arrowwood, not a named plant of arrowwood like Chicago Lustre. What they don't say (and maybe don't know) is whether they have a seedling of Viburnum dentatum. THAT MATTERS. If they know they have a seedling (grown from seed, not just a little plant), then they have a genetically distinct individual of Viburnum dentatum from a known provenance. If they just have an unnamed plant, it could just as well be a clone depending on propagation method. And on we go...

NEXT: Propagation....every Chicago Lustre is (should be) identical to every other Chicago Lustre because the plant is reproduced VEGETATIVELY (clonally or asexually), generally from cuttings that are then rooted. Species plants of arrowwood can also be produced this way. This is the trap that many individuals seem to fall into when claiming that they have "the species" and not necessarily knowing if they have seedlings or simply unnamed but clonally-produced plants. When plants are produced from seed (SEXUALLY) this means that there has been some genetic mixing between two parent plants resulting in seedlings that are related to but not identical to the parent producing the seed. Individually, these seedlings are no more or less capable of self-pollination. Are you worn out yet?

If you purchase and plant more than one arrowwood that were grown from seed (thus similar but not identical), then these will be fine for providing cross-pollination conditions if they have overlapping bloom times, which they should if from the same seed source.

NEXT: In a previous life, there was a question elsewhere about what happens when buying plants from Oregon and from North Dakota sources. This was one of the best questions yet about getting to the crux of the matter. Overlapping bloom times is the critical factor. If plants from these disparate sources bloom with a month separating them, no dice. If they overlap, one should have oodles of fruit.

NEXT: Provenance is important, especially to northern gardeners and those who want to respect their efforts to reinvigorate native landscapes. You want a plant that is known to survive your conditions (soils, moisture, low temps), and some want plants that are known to have naturally occurred in their area. Viburnum dentatum has an extremely wide range of natural occurrence (provenance); a glance at Hightshoe's text shows a distribution map shaded from Cape Cod MA down the east coast to northern FL, and along the Gulf coast to east TX. Interior areas shaded include most of those states bordering the Atlantic Ocean and Gulf of Mexico, as well as minor areas in AR, MO, TN, KY, and OH. This map is just for V. dentatum. Varietas of V. dentatum and its allies (like V. molle, V. rafinesquianum, V. recognitum, and V. bracteatum) extend this range even further. You want to know these things when selecting plants for ND, or NH, or GA. The different clones of Viburnum dentatum come from many areas; no wonder they don't all bloom at the same time! This applies not only to my garden bloom times (I have over twenty different V. dentatum), but to the difference in WHEN they bloom for me and when they'll bloom for you. For me, arrowwoods generally bloom in May-June; for you, that may be a month or more later or earlier. The SEQUENCE of identical plants' bloom times should remain constant, though. If in KY mine proceed from Cardinal to Indian Summer to Northern Burgundy to Autumn Jazz, then you should have the same order of bloom in ND, or NH, or GA.

NEXT: I know several folks who will be again tracking bloom times in 2006, in order to help the DGers flailing about trying to match up some of their favorite fruiting plants. This will make life simpler in some respects (shouldn't be tough to have a start-to-finish list of all the clones' bloom times) but more confusing in others (seedlings, if not of known provenance, are going to be all over the place time-wise).

Is anyone still awake? Isn't this fun? My personal goal is to grow as many of all the viburnums as I can here in KY. Not just clones, but seedlings of known provenance too. Any that I learn to be invasive here will be eradicated, but there will still be many to permanently cultivate. These are great plants to look at, but also to learn from so that others can enjoy them successfully as well.

How close do the two different viburnum have to be to each other to get a good chance of cross pollination? I have two different viburnum that might work (mohican and mariesii) but they are about 150 ft apart.

Jomejamo

You didn't have to quit there, but I understand you have to take a breath now and again. BTW, I had to place a towel under my monitor because the Viburnum obsession was dripping out the screen.

I will vouch for increased fruiting in other plants. I have a Persimmon. (D. virginiana) that was bi-sexual and produced some fruit. Once the little one started blooming and proved itself a male, the fruit on the other tree increased 10 fold in number.

Bloom time. That is a sore subject around here. It is the answer to "Why don't we have Japanese walnuts to pick?" Knowing that if I got 2 trees from the same source in the same year they could well be the same clone, I odered from 2 different nurseries. One tree blooms 2 weeks before the other one. So since Juglans angustifolia blooms only last a few days, there is no overlap, there are no nuts. Hate when that happens.

After reading everything you have written for a long time, VV, I am still left with a question. I agree with what you say about self pollination. There are recognition molecules on the outside of pollen grains, and 'same' is almost always rejected in favor of 'other'. (Not true in cleistogamous flowers.) However, since that are so many Viburnums around (I might have 8 or 9 species here, and several incarnations of mariesii), why are no hybrids produced? You would think that there must be a lot of pollen floating around in the spring, why doesn't more of it go towards fertilizing a closely related species? I am not real familiar with these underused plants, maybe the fruit I see is hybrid. I just wonder if these hybridize easily so that one could get fruit by planting a red fruiting species near one of the blue- or black-berried species whose bloom time overlapped. (Using the color of the fruit only to illustrate that it is a different species.)

I am so sorry. I have written to the authorities asking for the duplicate posts to be removed. I was using a version of Netscape that locked up, and because I hit the send key several times thinking it wasn't going anywheres, multiple copies showed up. I am now using Nozilla and hope never to have this again.

I found that once you hit send, even though it doesn't bring up the next page, it's sent... ;-)

SB, whose V. nudum 'Winterthur' was totally killa after adding V. nudum species nearby

VV - do you consider the double file viburnum (plicatum) to be invasive? I listened to a lecture last
year where the professor told us that he felt that V. Plicatum would be put on invasive lists soon. I'd hate
to pull mine out & certainly have not seen any seedlings around my place.
Tam

I've not seen V. plicatum (the sterile form) or V. p. tomentosum or its cultivars self seed here, but it does occur with V. xrhytidophylloides.

Now I'll see if I can break the cycle of duplications and post this only once -- wish me luck!

Guy S.

I have also read reports of doublefile viburnum being invasive. I just bought one yesterday without researching it first but have not planted it. I'm still undecided if I should plant it or throw it out. Would they have the potential to be invasive here in zone 8 with our hot summers? From what I understand they require shade in warmer climates.

As I said - mine has not self seeded. I've had it for almost 8 yrs.

And the learning banks into a superelevated curve............see what you started, Guy?

Jomejamo: Mohican and Mariesii are pretty different plants, though they do overlap in bloom time here at the Valley (late April early May). You may have better success with a different clone of V. plicatum var. tomentosum to partner with your Mariesii (like Shasta, Shoshoni, Pink Beauty, others) and either a seedling V. lantana or a hybrid related to Mohican (like a V. x rhytidophylloides clone).

Distance apart? How far do your bugs fly? Closer is just about always better, but 150' is not much for bees and other insects to travel while doing pollinating for you. I always suggest co-opting neighbors who have insufficient viburnum collections to participate, increasing odds and productivity for everyone.

PennPete: good to see you here, harrassment in tow. Speaking of dripping.......soup went all about last night, due to feline misstep while "assisting" with the treatise being written. Quercus macrocarpa (see sommelier on my home page) is hereby banished from command central.

I'm trying not to mix messages with the Viburnum genus. It is NOT a male flower on separate plants from female flowers (dioecious), like Diospyros (persimmon) and Ilex (holly) generally are. It is a self-incompatibility issue in a monoecious genus (Viburnums do not "self" well) for whatever reason that a plant biologist or botanist can better explain. The comparison to your Juglans is more appropriate, I think.

As far as hybrid production: I bet if you grow out seedlings from all the seed you produce in a season, you'd have some hybrid plants. I don't know your whole collection; post the list and I'd venture ideas on what might be "pairing up" without your knowledge. In nature (species from around these parts), most of them don't have overlapping bloom times across species lines within particular regions. Additionally, I really don't think Viburnum as a genus wind pollinates at all, so the floating around of pollen would have to be with an insect assist. Finally, you said it, regarding like with like. There is probably a size difference in pollen from species to species and it may be physically impossible for species not closely related to pollinate each other (outside of a laboratory). A great goal of mine is to find Dr. Donald Egolf's writings and publications, and divine some of this relative arcana so that I can understand my plants better.

SB: Touche; vive la difference! Glad you're pleased.

Tammy and Escambiaguy: I do not have personal knowledge of V. plicatum var. tomentosum behaving as an invasive, but I don't live, work, and grow outside of KY. I'd recommend each of you contact your local/regional Exotic Pest Plant Councils, and learn what the current science is on these plants. Of course it will be a shame, if it is indeed accurate. V. dilatatum, an exceptionally ornamental introduced viburnum, is reported to be behaving badly in MD at least, and likely in other mid-Atlantic states where it has become entirely too at home.

As with any plant, take the time to learn about it and what all the terminologies mean. Invasive (where the plant ought to be banned from use) has a specific meaning, and it isn't that it just pops up as a seedling on occasion. Seedlings are one warning sign, though. And because you don't observe any on your property doesn't mean that the plant in question isn't misbehaving offsite where you don't see it.

The invasive discussion really needs to be another thread. Takers?

Just to try to put a positive spin on a touchy subject. If you had to choose a plant to be your local invasive headache, you could do far worse than V. plicatum tomentosum!

Additionally, some people are pretty loose with the term "invasive," using it whenever an exotic plant turns up in an unmown field. That's a whole different thing than the nightmares caused by buckthorn and honeysuckle.

Scott