I'm interested in knowing whether anyone has any experience, either casual or scientific, with this tropical milkweed: Gomphocarpus physocarpus (Syn. Asclepias physocarpa), common name Swan Plant. It's sold in the floral trade for its unusual seed pods, which are used in arrangements.
I found some of these plants in a greenhouse, and they were covered with monarch caterpillars and eggs. I took them home, and they certainly do atttract laying monarchs. However, I have noticed that survival at all early stages seems to be much lower on this plant than any other I've seen, either domestic or tropical. Many eggs don't hatch, of those that do, many larvae die in their first molt.
It could be that this plant's toxicity is simply too high even for monarchs, or that the plant also attracts predators. I would get rid of it but I'm curious about it. Oddly enough, I found a Web site for educational monarch rearing kits, and this plant was sold with the kit. So somebody thinks it's actually good for them. Any thoughts?