It's a type of epiphytic cactus, like Rhipsalis is, but it's its own genus. From Wikipedia - I too had no idea there were so many species. Hylocereus calcaratus - Costa Rica. Stems soft, green with distinctly lobed stems. Flowers 35�"37 cm long, 20�"30 cm wide. Hylocereus costaricensis - (incl Hylocereus polyrhizus of gardens) Costa Rica and Nicaragua to Peru. Stems waxy-white without horny margins. Flowers ca. 30 cm long with large bracts, usually with purple margins. Fruit red with purple pulpa. Hylocereus escuintlensis Guatemala. Stems green not glaucous, brown-margined. Flowers 28�"31 cm long, 24�"36 cm wide. Hylocereus megalanthus - Stems green, slender without horny margins. Flowers 30�"38 cm long with large flattened tubercles and small bracts. Flowers similar to Selenicereus. Fruit yellow. Hylocereus minutiflorus - Guatemala, Honduras. Stems green. Flowers with rigid spines at base of flower, 5 cm long, 8�"9 cm wide, white. Hylocereus monacanthus - (incl. Hylocereus lemairei) Costa Rica to N South America. Stems gray-green without horny margins. Flowers ca 30 cm long, petals white, tinged pinkish near base or entirely pink. Tube with distant bracts. Stigma lobes usually forked. Fruit red with purple pulpa. Hylocereus ocamponis - (incl. Hylocereus guatemalense, Hylocereus purpursii) Mexico & Guatemala. Stems white-waxy, margins horny, spines needle-like, to 12 mm long. Flowers 25�"32 cm long with white inner petals. Bracts overlapping, with purple margins. Hylocereus setaceus - Stems green without horny margins, rather spiny. Flowers 19�"22 cm with small tubercles and bracts. Flowers similar to Selenicereus. Fruit red. Hylocereus stenopterus- Costa Rica. Stems thin, soft, green. Flowers 9�"10 cm long, 13�"15 cm wide, tube short, tepals purplish red. Hylocereus triangularis (incl. Hylocereus cubensis). Cuba, Haiti, Dominican Republic, Jamaica. Stems green without horny margins, slender. Flowers ca. 20 cm long, base with wide overlapping scales. Hylocereus trigonus - (incl. Hylocereus napoleonis, Hylocereus antiguensis). West Indies (Puerto Rico south to Grenada). Stems green without horny margins. Flowers ca. 22 cm long, 21 cm wide, base with small, narrow, widely spaced scales, sometimes spiny. Fruit red. Hylocereus undatus Native habitat unknown and maybe of hybrid origin. Stems green, margins undulate and horny. Flowers 25�"30 cm long, white with green outer tepals and bracts. Fruit red with white pulpa. This post was edited by cactusmcharris on Tue, Jul 30, 13 at 23:57

Im just taking a stab at this. I'd say that given the appearance of the tree and where it's planted, it was originally the rootstock of a flowering quince (ornamental shrub), which I THINK is often grafted to a pear rootstock. So what you may have is a "wild type" pear tree. At any rate, it's too close to the house and I would move it. It might not be worth the trouble of trying to save it, especially since you are not sure what it is. You might wait a year and see what it looks like in the spring, if it blooms, etc. But it is too close to the house...you'll have trouble with the siding staying damp and if the trunk gets much bigger, you wont be able to get around it to do maintenance.

I love this blog on the Christmas tree debate. Well, I will be 80 this September and I never put up a Christmas tree last year because my beloved Westie passed away around last Thanksgiving, then this year there was a family issue which has not been resolved and also lost our beloved Scottie; therefore, I feel like Christmas has never really happened yet. I have a beautiful tree in my dining room with children's vintage toys under it and a beautiful flocked tree, more formal, in my living room, both decorated with 60 years of collectible beautiful ornaments. I don't light them unless for a special occasion, but they give me inner peace, comfort, and helps me de-stress. I know that some people think this is strange, but I remember reading when Carrie Fisher passed away, she always had a tree up year round. At my age, I think everyone should do what makes them happy!

I'm so sorry your job has become such a nightmare. It's hard when something that is going to be a great improvement in your home becomes such a trial to get through. I'm with you in spirit - we started what was allegedly a four-month job on December 2, 2013. We knew at the time that six months was more realistic, but we would have the space back by July 4th, no problem. It's one year later and we're still not done (should be about two weeks out). We're close enough now that friends come by to look at the kitchen and say "oh, you're going to love cooking here" and, like OOTM Mom, I feel no pleasure or joy or anticipation, just "whatever, yeah." Every day is a day closer to finished. Hang on.