It is more than likley passiflora caerulea var. "Constance Elliott", which is an all-white cultivar. I haven't heard it called "white crown" before, but since it is a white selection of p. caerulea, which is commonly known as "blue crown" passionflower, it certainly makes sense. I would not plant the "white crown" in the ground outside of zone 8. I have heard reports that it is a wee bit LESS hardy than "blue crown".

I have a Constance Elliott. It has been very hardy for me in zone 8. I have lost a few of the "blue" caerulea plants to root rot when we had an extremely wet spring but so far all the CE have done really well. The flowers on in tend to be a bit larger than the blue form. I think it is one of the more beautiful varieties. Another plus for it is that it is evergreen in zone 8. Even when we had a late ice storm a couple of years back and it had ice hanging from its buds it came thru without freeze damage.

Patsy

does anyone know the name of passi having white 3" fragrant flowers, large, tri-lobed light green leaves and yellow, hollow fruits? I let it die back after hurricane wilma and didn't keep a cutting. it rooted easily from cuttings and did not grow new plants underground. I miss it so. the gulf fritilary butterflies loved it, but it was able to outgrow the cats' appetites.

My first guess would be P. 'Quasar' due to the white flowers with always empty fruit. The only issue is that it has both 3 and 5 lobed leaves. Suncrest is a distributor. Take a look and see if that looks right. If so, call some of your local nurseries, and ask if they order from them. If so, they may be willing to special order it for you: http://www.suncrestnurseries.com/descript/passiflora.html

Good luck,
Eric