I have had several clematis texensis for years and they are wonderful. Joy Creek Nursery is the only place I know to get this (online catalog) and it is listed as "the Tarpley River Form". It grows to 20' and is not as dense as most clematis so you can enjoy the dark stems. The flowers are 2" tubular bell shape, bright scarlet red with very thick petals and it blooms all summer into the fall (Wisconsin). What I love most is that it attracts hummingbirds even better than putting out feeders! My first one climbs and rambles all around my back porch so I have the hummingbirds right there with me. I read once that this clematis is the parent of all clematis. Although it originated in Texas, it is extremely winter hardy (zone 4).