Ask Mr. Smarty Plants

The only true native of the three mentioned is Passiflora incarnata (purple passionflower). All we could find out about cultivar 'Elizabeth' was what you already knew, that it was a hybrid of P. incarnata and P. phoenicia. Beyond that, it gets a little murky. We found only one mention of phoenicia and this was in Dave's Garden, a forum, where it was referred to as a cultivar 'Ruby Glow' of Passiflora incarnata (purple passionflower). The pictures with that site were of a reddish-purple flower, which could have been a sport or a mutation of the original species that was developed further by a commercial nursery. So, we are looking at a "double hybrid," making its true characteristics even harder to determine. However, we are of the opinion that the clematis is a late-emerging vine in the Spring, and the late frosts may have inhibited it even more, although it should still regrow from the corms or tubers, which are protected from freezes by the warm earth. On the subject of weak blooms, this plant needs full sun to really bloom well, although it will grow in part shade. And, cut out the heavy nitrogen applications. Nitrogen makes plants very happy, they leaf out heavily in response to it, but don't get around to flowering much. Native plants seldom need fertilizer, as they should already be accustomed to the soils and climate in which they are growing.  If the plant doesn't start showing some signs of life by May 1, it's dead.