When I purchased this tree in 1989 it was labeled Catalpa bignonioides. However, online research indicates it may be Catalpa speciosa. Further details, if needed, could be provided. TIA
Catalpa bignonioides (common catalpa) and C. speciosa (western catalpa) are notoriously difficult to differentiate when small or without flowers or fruit. Vigorous, juvenile leaves may be uncharacteristic of adult foliage, for example. In general, C. bignonioides is less common locally, smaller and much less hardy. A number of authors give helpful hints on the differences. Some examples are printed below. Keith Rushforth in Trees of Britain and Europe (Collins, 1999) states that C. speciosa makes a better tree; that individual flowers are larger, but that there are fewer per inflorescence; that the rubbed leaves do not have the unpleasant smell of C. bignonioides and that the leaves are more neatly ovate-triangular, without a rounded shoulder. The late Alan Mitchell, in Trees of Britain and Northern Europe (Collins, 1988), states that C. speciosa has grey, deeply ridged bark, while C. bignonioides has brown, scaly bark. In England, western catalpa also flowers in June and July, nearly a month earlier than the southern species. Gerald Straley, previous Curator of Collections at UBC Botanical Garden writes in Trees of Vancouver (UBC Press, 1992) that the flowers of western catalpa are just finishing when those of common catalpa are starting in the Vancouver area, and that the individual flowers are larger with fewer spots. Straley notes that the crushed leaf smell test does not seem to be reliable in this climate. Both species are present on street plantings (where they can be readily compared) in many parts of Vancouver, particularly in west Kits.
I've spent many hours on Catalpa today, and I'm not sure in the end if I'm going to ask a question or just add what I think I know. My problem is that for the Catalpa that Straley says blooms several weeks later than the other, a location specifically listed in the book was the first Catalpa to bloom this year. And I also found the Stanley Park trees listed to be confusing, based on blossom size and blooming time. But by now, my examples are all messed up. So next year. [Edited]I see what's wrong - that first location is listed for both species. Maybe I almost do understand this. I'm adding photos for ones I think I do understand, at a very easily accessible location for anyone in Vancouver. Thornton Park, across from the train station on Terminal Avenue, has two Catalpa speciosa, at the north end of the park. I'm assuming this ID because they're completely finished blooming today, August 1, 2012, and the leaves seemed relatively small. There are only two flowers left, and none that I could measure. I did measure some Catalpa flowers at almost 6cm across two weeks ago. At the south end of Thornton Park are two Catalpa bignonioides, I'm assuming because they're at peak bloom today. The leaves are large, the candles are taller than wide, and the flowers are no more than 4cm across. Nadia in White Rock had been wondering about a tree near her, and asked me to take photos and post them for an ID, because the flowers seemed so much smaller than what she'd thought were usual - they were only slightly larger than a loonie (which is 2.5cm). I think it's Catalpa bignonioides. While you're at Thornton Park, you can also compare the Catalpa to the Paulownia tomentosa that's in the the middle of the park. The leaves look pretty similar to me, but the round fruits (instead of long pods) are the give-away. And to round out your investigation, the Catalpa and Chilopsis hybrid, xChitalpa tashkentensis I posted last year in September is in bloom now. It's right opposite the station entrance.
The best distinction I've been able to come across seems to be mature pod diameter: Under 1 cm = likely C. bignonioides Over 1 cm = likely C. speciosa But I'd not be too surprised if there is some overlap in reality.
Catalpas in White Rock I decided to post two catalpas in my area. Actually they don't let me sleep well if I don't know what they are. They are both big mature trees with nice leaves and beautiful flowers, they bloom almost at the same time this year, last year second one may be later a little bit, but second tree is on the north side of the street, first one is located in an open area. In White Rock Sport center, don't look at name On 152 Str. between 24 and 26 Avenues both leaves and flowers, first one is on the left, second is on the right, flowers are from the ground
I wonder whether Nadia's second tree, on 152 Str. between 24 and 26 Avenues, by the dark look of the flowers, lobed leaves and the slender beans, is Catalpa x hybrida. I have to think that the lobed leaves might not be that definite a distinguishing feature. There were lots of lobed leaves on 10th around Macdonald, but they were on trees like this one that I'm pretty sure is Catalpa speciosa. A lot of the leaves are larger than my 20cm hand span, they're in bloom at the end of June instead of in late July/August, flowers are 6.5cm, pods (not pictured) are mostly broken up but are not skinny.
In some cases for IDs, timing is everything. And this is a good time to figure out Catalpa trees. According to the Vancouver Trees App | UBC Botanical Garden, Catalpa speciosa blooms in June, and the trees are taller than wide, with a long straight bole. These photos are from street trees in the West End, on Nelson near Gilford, where the out-of-print Trees of Vancouver (Straley, Gerald, UBC Press, 1992) says they are. They have totally finished blooming, but there are still flowers on the ground. All the branches are way higher than I can reach, so I couldn't have photographed them in the trees anyway. This Catalpa bignonioides is also where Trees of Vancouver says it is, on the north side of the underpass to Stanley Park, at the end of Devonian Harbour Park. As wide as it is tall, with a shorter bole, it is just starting to bloom, maybe 15 open flowers today. These are supposed to have more purple spotting, but unless things change with later flowers, I'm not finding that very convincing. These are also supposed to be less frilly; I would say they are evenly frilly, whereas the C. speciosa flower margins are more irregular, at least in the ones I saw today, pictured here.
Catalpa bignonioides, adding more photos. Here is another photo of the tree above, at the Coal Harbour end of the Georgia Street underpass, in full bloom for a few days now. Nearby, at Coal Harbour, where the seawall enters Stanley Park, is another of the same species. Very funny. The pods are way up there, and they are dehiscent, so no closed pods reach the ground. Really, exactly none. I found some seeds, though, and whatever you call the inner bit that they are attached to. Speaking of Catalpa, I finally found a page that says this jungle gym was a Catalpa from right nearby, downed in the 2006 storm. This looks like a "short crooked bole", which the Vancouver Trees app says distinguishes C. bignonioides, so that's what I will be calling this.
Beautiful tree Wendy. If anybody in the UK wants to see a lovely specimen, then do visit Westonbirt in early 'August'. The flowers and especially the seed pods are to see to be believed.
