Key, Mexican, or Bartender's Lime, Citrus aurantifolia 'Swingle'
What ever you choose to call it, Citrus aurantifolia 'Swingle' is a steady and prolific producer of small (1.5" diameter) acidic fruit with a strong and complex flavor. The size is just perfect; one lime per avocado for guacamole. Though ours is on true dwarf rootstock, it apparently doesn't grow all that large anyway. Ours is a little over six feet tall and 5 feet wide.
I got the tree in 2004, and kept it in a pot for a couple of years. Like all my potted plants, it was miserable--half defoliated and yellowed, so I eventually gave it a spot in the ground where it has been happy, healthy, and productive. I got no fruit from it when it was potted, and it took about 2 years to recover after I got it into the ground, but it's been producing all the limes we can handle since then. We ran out of lemons for lemonade, and turned to limeade as a substitute. It's surprisingly good, no more like commercial limeade than a home-grown tomato is like a store-bought one. It has a more complex flavor than the larger 'Bearss' limes. The ripe fruits fall off in a slow steady manner, a few at a time. Some are seedy; most have one or two seeds, a few have none.
Though it is called a 'Mexican' lime, it's from the Malaysian/Indonesian part of the planet. There's some interesting information here; the bit about the fruit being saltwater pickled and shipped to Boston as a popular snack for schoolchildren is kind of--huh? Why Boston? Why school children? What about Irish policemen? Why Boston and not New Haven? How many other strange foods were fed to school children without my knowing about it? But I digress.
According to the Sunset Western Garden Book, this is a very cold-sensitive plant. Ours has experienced a few light frosts, and came through just fine--no apparent damage at all, so perhaps Sunset's idea of cold is colder than my idea of cold. The other possible disappointment is a surprising lack of fragrance to the flowers. We were spoiled by the exquisite fragrance of 'Meyer' lemon and 'Valencia' orange blossoms, and expected something of the same heavenly scent from the lime flowers, but--nothing. The fruit itself however is aromatic, I can smell the limes on my fingers after I pick them up.
About the easiest pie recipe ever is Key Lime Pie. The standard is a can (around fourteen oz) of sweetened condensed milk, four to five ounces of lime juice, two to four egg yolks, and eight ounces of cream cheese all blended together, poured into a graham cracker pie crust, baked for 10 minutes at 350F (for egg safety), then chilled. Quick and simple. One variation is replacing the eggs with a cup of heavy whipping cream, blending the mix until it becomes something like whipped cream, and chilling the pie (no eggs means no bake). If you wish to substitute Cool-Whip for heavy cream--well, let's not go there. An envelope of unflavored gelatin will make the whipped cream variation more "set". I seem to remember a version where the eggs are replaced by one or two envelopes of unflavored gelatin and the pie is simply chilled, but I could not find that version and cannot confirm it. Regular lime juice works just as well as key lime juice.
All in all, for the amount of space it takes up (not much) this is a good, petite tree to have around. Most citrus trees are quite ornamental; this one is no exception.
This has nothing to do with Key Limes, but Abraham Darby was looking blatantly apricot today. Usually he's a pink-peach-yellow blend, and in spring he can be very pink, but today he was overwhelmingly apricot. Moody boy!
'Pure Poetry' is another rose that varies quite a bit. It was looking pretty apricot, too.