Oh my, what a gorgeous, fun plant! I have never seen one of those, although have seen what I believe to be Pride of Madeira blooming on the way to my DD's school. I went to DG's plant files and saw a good write up on this by palmbob. I hope it is 'kosher' to quote his comments:
This is an amazing plant when it finally flowers (guess that happens every other year)- I have seen these grey, tall, weird plants at the Huntington gardens for several years... most have fallen over by this time of the year, but this time they finally flowered. Amazing. Grown in the drought tolerant garden, I assume these plants are extremely drought tolerant.
I finally obtained a small plant, about 1' in diameter (looked a bit like a puff ball- nearly a complete sphere) in a gal pot. Planted it in the cactus garden and it barely grew over the following 12 months... but then, in April the following year, it shot up, growing over 1" a day and is now, only 6 weeks after it started growing, about 6' tall and an impressive tower of flowers, arranged on unfurling flower stalks that are themselves arranged in a spiral pattern around the plant. Bees are swarming this thing and it's quite a sight. Sadly I know it will die soon after, but perhaps seed will germinate and it will show up somewhere else?
It rained late in the season (May) and the plant was obviously too top heavy to deal with it... and crashed. Recommend, if you water this plant (and it's extremely drought tolerant so no need to when flowering normally), don't water the crown/flowering part of the plant.
These plants appear to monocarpic... all flowering individuals are dried up deceased skeletons just 2 months later... so how do they reproduce?
Here's how: later in the year- once flowers done, they dry up, and the entire tower usually falls over (I staked mine up however). The flower parts dry up and turn brownish, and all end up having a small black seed in the middle of them, about 1-2mm in size. I guess as they fall, the seeds are dispersed (or eaten) and they spread that way.
I cut off the flowering portion of my plant, since the part below seemed healthy still, and I wanted to see if it would live another year and flower again. To my surprise, it did flower again, but middle of the summer. I am sure the entire plant is a goner, now, but if you don't mine haveing a hacked off tower in your yard for a few months longer, you might get a second flowering out of your plant.
Sure enough, by the end of August I had to dig up the carcass and toss it. However, literally thousands of seeds have fallen in the cactus garden... we'll see if any of them make it.
A word of caution: the dried flower parts are worse than cactus spines; do NOT handle them without gloves or some protection. They easily penetrate skin and are very difficult to remove and quite irritating. 'They' are gazillions of itty bitty little spines that aerosolize as well as adhere to all skin surfaces... so breathing with protection might be recommended, too, when removing one of these dead stalks.
