More like 'eternal' than 'perennial' when they're happy. They spread by seed or sharply-pointed runners which will easily go through the bulbs of other more-preferred species. And their older bulbs can go down 12" or more, like a string of beads. Do brilliantly in a sandy/silty soil. Don't mind shade but you'll get more leaves than flowers. Calistoga is not kidding. They're delightful - in someone else's garden.

I don't think it's Tilia henryana. Typically the "spines" of the soft spine like teeth are much longer on T. henryana than the leaves in the photo. You can find T. americana(Basswood, American Linden) with leaves with small soft "spine" like teeth like the leaves in the photo. The leaves look too large for T. henryana, which top out at about 4"x4"(10cm x 10cm), to me also. They look much closer in size to T. americana, which range from 4"x4" on the small side up to 8"x8"(20cm x 20cm), to me. Also, T. henryana in cultivation has so far been a relatively small tree in the 30' to 35' range(roughly 10m). Lastly, I'm doubtful that T. henryana(considered zone 7 hardy usually) is hardy in the zone 5 Brookfield Zoo which has seen temps as low as -20°F(-29°C) within the past 12 years or so(surely within the lifetime of this tree). So, I believe this is a Basswood tree(T. americana).

Actually I don't think it IS Pyrostegia, which is a vine with pronounced tendrils, , and your plant has much larger ribbed leaves. Ian can you have another look, I think it might be some sort of Acanthacea - justicia or something similar.?

Aha! That is it! I knew it started with an X.........thank you so much! A friend in Pearland took this photo and sent it to me - from a new Mexican restaurant. If the food is as good as the landscaping - I cant wait to try it! Thanks again!! Judith