Wild Forager,

Now you know I cannot pass up the chance to talk about the Apios genus!(grin)

Chances are high that the A. americana will out live you! According to the USDA it has a moderate lifespan in reference to other plants with the same growth habits. Here is a breakdown of the lifespan scale:

Lifespan (in years) of a plant:
Short Moderate 100-250
Long >250

The A. americana mother tuber will increase in size each year. Yes, it will eventually die, but as you can see you will most likely enjoy this species for the remainder of your life. As for its size. I have read and heard varying accounts for the size of the tubers. Everything I have ever read about this species can be summed up as: tubers can be anywhere from the size of a peanut to the size of a basketball for the mother tuber.

But honestly, unless someone has had one growing for more than 20 years there is no way to tell. According to the USDA, 20 years is the height of the maturity of the Apios americana in which it will not grow any taller than it is at that time. That is not to say the tuber will not grow any bigger, just the vegetation will not get any higher than it is at year 20. Wouldn't that be an interesting find, the oldest A. americana? Then we would know the actual size the mother tuber can get! I have no scientific resources for a definitive answer to that part of your question. (sorry about that)

Hope this helps!

I have an idea. If you are interested in doing this anyway. You could measure the length and girth of the tuber each year for about 3-4 years. Then you can project the maximum size of the tuber at its 20 year maturity growth age based on the average girth and length between the 3-4 year period. Might be the only way anyone will ever know for sure.

Which that actually makes me wonder too, does the maximum size of the mother tuber vary between a diploid variety and a triploid variety?

See what you started! LOL

I can't wait to find out. Maybe this tuber will become a family heirloom ;)

A family heirloom I am sure! Given how long it will live, many future generations of your family will enjoy it! So, you going to do the measurements? LOLA simple regression model will be ample to predict its size at 20 years.

WildF, did you ever get any pods or viable seeds from it? Do you container plant it? How do you overwinter it?

I have been growing Apios americana for the last five years, letting them overwinter in my central Connecticut garden. The largest tubers seem to top out at the large chicken egg to slightly smaller than a tennis ball stage. At that point they either don't make it through the winter (if they get exposed due to frost heaving) or I think I've sliced them while working in the beds. Since they spread fairly easily, I've never worried about keeping one aside. I doubt the individual tubers would last anywhere near 20 years if left in the ground. My understanding is that there is quite a bit of genetic variation in the plant from region to region. My plants flower profusely, but have never set seeds. Since they all came from one tuber, I suppose they either need a male plant or another plant to pollinate them.

Don,

Thanks for the information on the size of the tubers! As for yours not setting seeds, they do not need a male flower as they are self pollinating, however, as you have mentioned the genetic variation from region to region does exist. The further north the species is found it has been discovered that the more northern varieties are triploid through an evolutionary change (it is suspected this is to protect them in colder climates). Because it is triploid then it is "sterile" for seeding. It is grown through vegetation only.

The more southern varieties will seed because they are diploid in nature. So those varieties will reproduce both sexually (seeds) and asexually (vegetation).

And this is why I wondered if the size of the mature tuber would vary from the diploid and triploid varieties. I would love to come across someone growing it for at least 5 years in the south and hear how large theirs is.

I have one sitting in a box on my kitchen counter now that is the size of a very small egg (maybe 2.5" in girth), and I have not placed it in the pot yet to get it growing. This one came from a more midwestern range.

Interesting stuff here WildF. Thanks for posing these questions!

Agrigirl

happyday, it has yet to make any pods or seeds. It grows very well in a container (though I have no experience with it in the ground). I overwinter by putting it into the fridge in a freezer bag with some moist potting mix (do not seal the bag or it will mold (though not enough to kill the tuber). I air the bag out once a month just to be sure it's not getting moldy inside.

I will definately measure it this year before it goes into the ground and after.

How do the tubers taste, and how do you usually prepare them? And one more awkward, but necessary question,.....do they give you gas?