This blog is about growing tropical-looking plants in the Phoenix, Arizona area



August 1, 2015

How cycads, like sago palms, reproduce


If you're like most people, you learned about the birds and the bees when you were a kid. That is, bees pollinating flowers, and birds, uh, singing, I guess. Can't say I ever really understood all of that. For plants, that is. And it wasn't until I started learning about cycads, like sago palms, that I really ever gave much thought to the reproductive processes of plants.

Since this is the internet, I won't use the "s" word. I don't want the Google bots getting confused about what I am writing about here! But that's what I am going to talk about here today. Stop that giggling back there, please!

Cycads are in that rare group of plants that have two genders. Yep, a cycad is either a girl plant or a boy plant. Of course, most plants on planet earth have both male and female parts, but cycads are like people, and in order to reproduce they need to do the same thing that people need to do - they need to be nearby a plant of the opposite gender at exactly the right time that the other plant is ready to reproduce. Not a very good system for plants, which is why dioecious plants are rare. By the way, if you Google "dioecious plants", you'll see that there are others. But mostly I'm interested in cycads.

Cycads don't flower, they cone. Yep, like pine trees! They have to reach a certain size and maturity to do this (that's a male cycas revoluta - a sago palm - in the image at the top of this post), and the opposite-gender plant has to be nearby in order for, well, you know. Please stop the giggling!

If you've seen those strange growths coming out of a cycad, like your sago palm, you are seeing a cone. The females ones are large and round, the male ones are long and skinny. If it actually looks kind'a like a pine cone, it's a male. Females look like something from a science-fiction movie - wider and flatter.

Cones on a male dioon edule cycad

In my yard I've seen my cycads cone sometimes. My dioon edule is a male, and he cones every couple of years, but, alas, as there are no females who are coning at the same time that he does (or at all in my garden!), he just sits there, lonely. Cue the sad music!

In the wild, cycads are pollinated usually by the local beetle population, sometimes by wind. In cultivation, they're pollinated by people with brushes, gloves, and a lot of care.

So, the chances of finding viable seeds in a female cone of a cycad, just at your local park, are pretty slim. And really, cycads grow so slowly that you won't really have much of a plant to look at for a decade or two. But I don't want to discourage you! Many rare and endangered cycads are being grown by collectors all over the world, and that may be the only hope that this rare and interesting plant has to survive on planet earth.

Cycad Seed Bank information is here http://www.cycad.org/members/seedbank.htm
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