Thanks all. Note that in addition to being a gardener, I love birds and in fact try to attract them to my yard via feeders, birdbaths etc. So I would never want to wantonly remove a haven for birds. However, I also understand the value of trees, which are unfortunately grossly under-appreciated, and their contributions grossly misunderstood, by most people in NYC. So this is why if I think a tree is at risk, that I should do what I can to save it. I also read a terrific book recently, "Bringing Nature Home: How Native Plants Sustain Wildlife in our Gardens", and it talked about this very thing...how non-native plants (such as English Ivy) can dessimate native plants/trees. As for those who mentioned that sometimes the ivy itself helps to anchor a tree, well I'd imagine that if a tree needs that kind of help in keeping upright, chances are it wasn't much longer for this world to begin with. But I'd suspect that in many instances, it's a case of ivy simply growing up and eventually masking an entirely healthy tree, and that eventually the ivy will block out its ability to take in sun. So at this point I still plan to cut as much of the ivy as I can without damaging the tree bark itself. Tx!

It depends which part of Pasadena you're in. Some places get more frost than others. In the milder parts, it will survive every Winter. But to be honest, nasturtiums look terrible after about a year, so I'd recommend something else, like a good passion vine. There are many different kinds and they grow very quickly. If you like fruit, look for passiflora edulis "Frederick", it's available at most nurseries.

I was going to recommend a climbing rose. But most of them have thorns. Unless you go for Zephirine Drouhin rose, which is virtually thornless. However, I don't know how it will fare in your climate. You can check on the rose forums. There are several fragrant clematis. Clematis Montana, Clematis rubromarginata, Clematis sweet summer love. Other vines, are Moon flower (Ipomoea alba), and other less fragrant honeysuckle vines. You need to check for the toxicity of some these vines, for children and animals. Go to the fragrant plants forum and ask for more advice.

Coral honeysuckle (Lonicera sempervirens) is semi-evergreen in Dallas, so might hold it's leaves better in your more southern location. Big show in spring, then sporadic throughout the summer. Grows fast, but takes several seasons to really fill out. I know there are red, yellow, orange, and pink cultivars, though may be more. Hummers love flowers, other birds like seeds. Though not much scent. Very easy to manage. I've not grown evergreen clematis (c. armandii), but seen it used in our neighborhood. Early spring blooms have a very nice scent, though don't seem to stick around very long. Foliage is attractive and evergreen. Don't know about aggressiveness. Might be worth a look.