Exotic plants, oaks specifically

[Jim]

I know this is sort of an odd topic, but I had to bring it up. I get palms, and lawns, and citrus, and many of the non-native vegetation planted in the desert and like many, I enjoy it. I also understand and enjoy live oaks being planted in the desert and think they make excellent trees to plant in parks as they can form a closed canopy grove of oaks if watered well and allowed to grow together. One thing that surprised me, was seeing scarlet oaks planted in parking lots north of Tucson, say in front of the Radio Shack on SR 77 north of Tucson, in front of the Fry's up by Catalina SP. They look nice and can probably develop into nice trees, but it really seemed odd, given that they are from places much cooler and wetter. I noticed a few planted in Las Cruces, too, for example in front of the Best Buy near the mall in Cruces. I guess we don't have many oaks in Alamo as the soil is almost pure lime and the water is so alkaline. We have a few live oaks, and they look nice and are doing OK, but they look better on the igneous derived soils. On the north side of a bank in town, we have two Bur Oaks planted and they appear to be doing quite well. I can't think of an odder thing, than to move to a place that averages less than 10 inches of rain a year, and plant stuff that belong in the mid-west or south. I enjoy those oaks, though, despite realizing they are totally inappropriate. Either way, at least they can grow here. The Canary Island Date Palms planted over here still look bad from the winter cold, and the ones in Tucson all had a nice flush of bright green leaves. This concludes my rant.

[azbackpackr]

I always wondered what those trees were (the scarlet oaks).

[Jim]

Turns out those oaks planted by the bank are Overcup Oaks, not Burr Oaks. They look very similar, but they lack the corky ridges on the twigs, the burr projections on the acorn, and the leaves are a little different. I'm surprised they look as good as they do, planted where they are planted. Basically they are in our limestone we call soil, and are irrigated with alkaline water. They have a gravel dressing over a weed barrier, so they aren't getting nutrients like nitrogen from lawn fertilizer or any other plants which are being fertilized. Still, the leaves are a deep green. The species is primary a Mississippi basin bottom-land species, but it appears to be more adaptive than I would have guessed. Nearby me and one street over, there is a yard with what appear to be 2 small scarlet oaks planted in front. One looks OK, but one is very chlorotic. Being so close together, there could be a number of reasons for this that are not strictly related to high soil pH. This basin is probably one of the worst places in the nation to grow plants, as your choices are so limited, and this is almost entirely due to the water and soil alkalinity. Combine this with the high summer temps over 100 to perhaps 110 degrees, the low winter temps which some report to below zero and definitely single digits, throw in the aridity, and it's a small wonder there is nowhere near the lush vegetation you see in Arizona. Plants look better over in Las Cruces, or near Cruces, on the soil that is derived from the igneous material of the Organ Mountains.

[Jim]

As I am certain all HAZ members care deeply on this subject, I shall report on it further. Went to the movie theater in town the other day and observed that quite a few Overcup Oaks were planted in the islands in the parking lot, when it was built several years ago. There were some other tree species, too, but they weren't as interesting to me. I do not know where these trees came from, probably a tree farm back east, but they actually look quite good. Initially, I thought they were true White Oaks, Quercus alba, but I spotted some old acorn cups and realized they were not. I did some reading of the silvics manual, sort of like a Tobin's Spirit Guide, and learned that Overcup Oak is primarily a bottom land species who's wood is ranked mostly as trash, due to it's tendencies to warp, split, and otherwise fall apart in the drying process, but that it survives very well on Mississippi flood terraces. It is one of the few species that can survive root zone flooding for extended periods, and successive growing seasons. Despite this seeming love of water, the ability to withstand wet periods which actually translates to poor soil oxygenation and can mimic dry soils, as well as a flat root development, has led to it being used an ornamental, and in odd places like the desert of New Mexico, where it can do rather well with watering. How it does so well with our alkaline soils and water is sort of interesting, but that is true of any irrigated plants here. The trees look to have been planted about 5 to 6 years ago, and some are already nearing 20 feet tall. I'm not sure how they will look after a long, hot, dry summer, or how they will do in 20 years, but so far they seem nice, and if someone was willing to spend a lot of money watering one, they probably are nice in a yard.

[azbackpackr]

I have a paper birch in my yard. I have not seen another one anywhere in town. I have a catalpa tree, also, but there are a few of those around here. I also have some kind of maple in the back.

A local forester I know was surprised that my birch has survived. Apparently they often succumb to a particular disease.