I agree that it looks like Orontium. Here's a way to check: water beads up and rolls right off Orontium leaves. Because of this trait, some people call the plant "never-wet".

Congratulations on taking the next step! OK....where do I start. First, consider going bigger. A LOT bigger. Koi get very large, over 30" in length and need space. Koi should have between 300 and 500 gallons each, so at your planned 1600 gallons you could realistically expect to keep no more than 5 koi. If you can double that to 3000 gallons you would be much better off. Depth needs to be a minimum of 36", although 48" is much better. 36" isn't very deep for a 32" long fish. Bottom drains are a MUST. Koi are very messy animals and produce a lot of waste. Most of that waste will sink right to the bottom and sit there until you remove it by vacumming, or the bottom drain carries it to the filter. You can buy bottom drains, commercially made. All you do is set the base in a bed of concrete in the bottom of the pond and attach the pipe that will be burried under the pond and come up at the side of the pond where it ties into the filter. Lay the liner in and get it secured. Then cut a hole in the liner in the center of the drain. Use sealant to prevent leakes and attach the plastic ring that comes with it with the stainless screws they provide you with. I have installed 5 drains in my own ponds and never had a leak. Get a 4" drain...anything smaller just won't move enough water. small koi will coexist peacefully with plants.....but the bigger the koi get, the more they will damage the plants. Koi love to dig in the pots and shread leaves. That is just their nature. You can have plants that stick up out of the water (iris, cattails, etc), just use a heave pot and use heavy round river rocks all on top of the soil to keep the koi out. And you many find that as your koi mature, even the rocks won't keep them out. Rocks on the bottom are a HUGE mistake. They trap debris that should not be left in the pond to decay. they provide a safe harbor for bacteria and parasites to breed, and koi can become injured on them. Seriously....leave them out. They do not look natural to me at all. In nature, you do see creeks with rocky bottoms, but I have never seen a lake or pond with a rock bottom. I love the look of a black liner bottom. When you have a beautiful collection of colorful koi swimming against that black bottom, you see the true beauty of the fish without the distraction of the rocks. Besides....the rocks will get covered in algae and won't look as nice as you think. I prefer to see koi when I gaze into a pond and not green rocks. A good supplier of equipment is AZ ponds. You can find them on the web. They are a little short on customer service, but their prices are unbeatable. Oh yeah....you need a skimmer too. You may want to check out a website called koishack. There are many wonderful threads over there in the construction forum with loads and loads of pictures. I just completed a new filter for one of my ponds that works every bit as well as a $1500 nexus filtes and it cost me around $150 to make it. Instructions for that are over there also.

Steve, if you don't get an answer here, or for addition exposure for your question, you might also post this in the Fruit and Orchards Forum. Similar topics concerning pawpaws have been brought up there before, and I think some of the pawpaw growers may have done some research on this type of thing.

Agree. I would love to put some of mine in my Japanese garden but the sprinkler system would hit the sarracenias and North Florida well-water is deadly to sarracenias. It might seem weird to put sarracenias in a Japanese garden but leucophyllas resemble a Japanese Jack-in-the-pulpit.