Paw paws (Asimina triloba) have relatively large, tropical-looking leaves. The size is in the range you're looking for.

Magnolia macrophylla has dramatically large leaves that would add a tropical touch (needs a fairly protected location, i.e. not windy).

Paulownia tomentosa. Huge leaves beautiful purple flowers before the leaves. Can spread but easy to control.

Here is a link that might be useful: Paulownia tomentosa

northern catalpa?

mimosa

Agree on the pawpaw, mimosa, Magnolia macrophylla, & Paulownia. Firmiana simplex is another big-leafed tree that looks somewhat tropical.

Golden rain tree, Koelreuteria paniculata, is a nice small tree that looks somewhat tropical and has nice yellow flowers in early summer (when few trees bloom).

Aralia spinosa and Aralia chinensis are nice, exotic-looking small trees but are extremely spiny and spread by suckering, so that's probably not much better than sumac for you. (BTW there is a very nice form of staghorn sumac, Rhus typhina 'Laciniata', which has finely divided leaves; I believe this cultivar is a female clone, and as long as there are no male clones nearby, it shouldn't produce fertile seeds, although it will still spread by suckering.)

These are all trees that perform well in the hot and humid summers of the southeastern U.S.A.; not sure how well they will perform in your cooler summers. Your best bet is to visit some of your local nurseries, garden centers, and especially public gardens (where you are more likely to see unusual plants) and see what appeals to you that will also do well in your area. This will also give you some time to consider whether you want to fill the space at all; you might decide that you like having an open area in the middle of your yard, or that a sunny patio might be a nice alternative to a shade tree if your yard is otherwise densely planted.

Why not a fig? I also live in PDX so we both know they definitely grow here... PLUS (except for the Paw Paw),you get something good to eat which the others won't give you.

CEDARS.. as far as I know really use up the dirt... suck up water and nutrients. So I would maybe think about not planting a tree this year. Assuming you were going to plant it in the same area.

Good luck and maybe I could see how your bamboo is growing/spreading since I've gotten my first one this year and still have it in a pot.
Jonna

All very good suggestions! Paulownia is a personal favorite of mine -- the flowers are gorgeous.

When I first read the question my immediate response was the Chinese Parasol Tree, Firmiana simplex, and was pleased to see that someone else had already suggested it. It definitely gives a tropical appearance to the landscape. I work as a horticulturist at the zoo in Memphis, TN, and we have quite a few Firmiana here on grounds. It has quite an exotic look to it compared to the shape and form of most of the trees hardy in this area, so it blends well with all of the bananas, elephant ears, heliconias, cannas, and other tropical-looking plants we use in our landscaping.

Of course you live in a completely different area than what I'm used to, so I can't say for sure how it would do there, but it's a pretty trouble-free plant here. Grows quite quickly, too, which is nice for trying to fill in an empty space.

The link below gives some good info on it.

Here is a link that might be useful: Firmiana simplex

What about Kalopanax? It gets large tropical looking leaves and cool flowers too.

Pic of entire tree:

{{gwi:1302548}}Leaves turn a nice yellow in fall:

{{gwi:1302549}}Good luck!

Travis

Here is a link that might be useful: Forest Farm

I was just looking through Steven Griffith's Big Leaves For Exotic Effect, and he has several recommendations not previously noted here for zone 8 and milder.

They include Idesia polycarpa (large heart-shaped leaves), Itoa orientalis, Liriodendron chinense (Chinese tulip tree, smaller than the American version), loquat and Aralia elata 'Aureovariegata'.

might want to check out cistus design nursery on sauvie's island they have a wide selection of hardy woody plants for the subtropical look.

love mimosas, but apparently they are "messy" trees - my dad had one and said he wouldn't put one in again... just thinking about your grass. :) My dad had one over his patio, and I think that's why he got tired of cleaning up after it.

cercis chinesis - Chinese Redbud It has nice largish heart shaped leaves and makes a pretty shaped lush looking small tree. (Of course it also has wonderful plush lavender blooms in the early spring before the leaves come out.)

Definitly catalpas
honey locusts and black locusts have an acacia-type look to them
magnolias
redbuds(on the smaller side)
royal powania(I think thats how its spelled)

Brian,

not necessarily big leaves, but whooaaa what an effect- Eucalyptus!!

I have several here near Wash ,DC and they are totally hardy here, so they would be no problem for you.

Forest Farm Nursery has a great selection of plants, and is in Oregon. They have a website too.

good luck

Boca Joe

Here is a link that might be useful: Boca Joe's Eucalyptus

Gums are common in parts of Seattle now, but have never been "totally hardy" here, nor in Portland. There are a few, small, leaning, alpine-type specimens left of a planting along I-5 near Salem that perhaps predate the big wipeout in 1990; a small Eucalyptus perinniana on Bainbridge Island is claimed by the owner to have been planted in the 50s. The usual experience is that the hardiest ones will grow for some time, only to freeze the next time it gets cold enough. This may be in 20 years or 20 weeks.

tulip tree

http://images.google.com/images?q=tulip+tree&ie=ISO-8859-1&hl=en&btnG=Google+Searchand

ginkgo

http://images.google.com/images?q=ginkgo&ie=ISO-8859-1&hl=en&btnG=Google+Search

Eriobotryia japonica - Loquat tree. Search this one on your favorite engine. Tough, hardy and evergreen!

Cheers, Barrie.

Robinia hispida probably prefers less heat than Robinia pseudoacacia, and has lavender pink blossoms which are a little showier. How about red buckeye, Aesculus parvae or other buckeyes? Chilopsis? Don't know how well these are adapted there.

corkwood (leitneria floridana) looks like it belongs in some steamy, tropicle jungle with its thin stem capped by a large rosete of buf leaves- as a plus, it forms clumps. hardy to zone 5b. i have seen some in cultivation and they looked very tropical to me- not to mention both are very hardy.

Fatsia japonica is rather "tropical" looking and is hardy in our PNW gardens. Large specimen are especially bold and look great all year long.

Cheers, Barrie.

It seems like all tropical-looking trees are messy, so we can't be too concerned with that. It's the price one pays.
Given that, I would urge a mimosa. Thailand is filled with types of mimosas, and I can verify that they compliment other tropicals splendidly. The blooms are lovely and fragrant and should last a good while when the weather isn't too hot. Also, it doesn't create enough shade to kill grass -- a dappled shade, really.
On the other hand, locust trees aren't messy at all, and are nitrogen-fixing.
Dennis

All of what is mentioned above is relevant.
My personal preferences go to:
***********************
Catalpa Bignonioides
Magnolia macrophylla
Liriodendron chinense
Eriobotrya Japonica
Paulownia tomentosa
************************
However, there is also one type that was completely omitted until now: big-leafed rhododendrons, which wild species look very exotic, and that can for some varieties reach 30-40cm length (calophytum, falconeri, sutchuenense, etc.); the problem with these wild species is that they are not cold hardy; they will probably withstand -10 Celsius, but I haven't experienced this myself; if it gets colder in where you live, you can still opt for a hybrid that is cold hardy, and that will sustain minus 20 Celsius or even more, e.g.:

http://s8860133.shoplite.de/sess/utn;jsessionid=15428477f756631/shopdata/0030_Rhododendron-Wildarten+und+-Hybriden/0010_Rhododendron-Wildarten+und+-Hybriden+von+A+bis+E/product_details.shopscript?article=0130_calophytum%2B%2B=27Arkona=27%2B=280=29

Another Portland resident chiming in here to suggest a favorite tree--Clerodendrum trichotomum (aka Harlequin Glorybower). I have seen these all over town so I know they grow well here. I'm trying to find a place to put one in myself.

The leaves are quite large and smell like peanut butter when you rub them, but the real treat is when it blooms at the beginning of August with the most beautiful white flowers that fill the air with a heady jasmine-like scent.

Then the subsequnt fruits are amazing jewel colors.

An amazing, very tropical-feeling little tree.

Here is a link that might be useful: Harlequin Glorybower

on that loquat site, what is this: ???

"If We do sell any more trees, fruit, or seed, we would want a signed agreement that states that any fruit, seed, or leaves harvested for commercial use and/or for profit, both now and any time in the future, would be reserved to Us and for Us unless or until We give up that right for specified reasons in writing for those certain specified trees produced from our fruit, seed, seedlings, and/or trees provided by Us. We will pay a reasonable amount for the harvested leaves and/or fruit. The amount to be determined at a later date. "

He sells me seeds, I grow a 10 trees for 10 years, sell the fruit "on the side", "just for fun" in a local farmer's market or roadside stand, and have to pay him in perpetuity? GMAFB

brian
what type of bamboo do you have?

Unautre: Great post...

Much of what I've seen listed doesn't match the height specifications or have drawbacks to them. Kalopanax is a good choice. Magnolia grandiflora is one of the best for the east coast, not sure about west. Some prunus lauroceraus cultivars have large glossy leaves and over 30' height (magnolifolia sp?). They might be good coll weather substitutes. What about lithocarpus henryi or castaneopsis-both cool weather adaptable broadleaf evergreens. A slow growing possibility is araucaria araucana. Bizarre! Perfect climate, with patience.

Christopher Lloyd praises Tree of Heaven (Ailanthus altissima) for its tropical appearance. I suppose if I didn't have several volunteers in my yard (as full-grown trees) and spend a lot of time pulling seedlings and runners I'd be more enthusiastic about it. It *does* have a sort of tropical look, it *is* incredibly tough and cold-hardy, and tolerates abuse like nobody's business.

But heck--in your climate zone you can choose from all kinds of cool stuff!

"Silk Tree",Albizia Julibrissin is my fave! It's leaves all close tight at night into a mere strip. Mine started flowering in July and I still have a few pink puffs on it. It is only in its second year in my garden and already is 10 feet tall and a really interesting shape. It is in a garden along with a brug and a "sundowner" phormium (and others) and looks super. I don't think it gets too big though, but gives wonderful dappled shade. Love all the suggestions..