Epiphyllum Oxypetalum - frequently called Queen of the Night. It is a night bloomer. The blooms range from 6" to 10'+ in diameter. They are very fragrant. The blooms close and wilt after they bloom. A one night stand.
They are easy to propagate. All you need is a leaf cutting 6" - 8" long. Let it dry a little by putting it in a cool place for a week or 2 before planting. Plant in a well drained pot. Use a cactus mix to make sure you have well drained soil. The hardest part is avoiding rot while the cutting roots. Keep the soil just barely moist. Don't fertilize the first year. After that use a low nitrogen fertilizer. Keep them just moist during the growing season and let them dry between watering over winter. If you are growing it indoors place it in a west or south facing window. If outside under a tree or patio works well. Keep them away from drafts from vents. If indoors or if you live in a region with low humidity they benefit from frequent misting. The plant is not very attractive but the blooms are stunning. They are natives of South American rain forest so they do best in warm, humid conditions with. Years ago I had several in hanging baskets under the live oak. If a hard freeze was predicted I moved them inside and put them in a west facing window. I lost them all one winter when I was out of town and an unexpected, freak, ice storm hit. The temperatures stayed below freezing for 3 days.
Take a few cuttings and try starting your own. I love "pass along" plants especially those with a history.
BTW - they probably won't bloom for 2 or 3 years.