Monday, June 13, 2011

So Tall Sotol



The desert is lusty with heat and flowers. After a couple months of daily measurable growth, the sotol (Dasylirion wheeleri) in our neighbor's yard is finally blooming. The fifteen foot tall stalk rises from a rosette of sawtooth edged leaves, luring swarms of honeybees (Apis mellifera) and tiny colletid bees (Hylaeus spp.) that come to gather pollen. I've watched the astonishing growth of sotol stalks for nearly a decade, but did not realize until recently that they are dioecious, meaning that there are botanical equivalents of male and female plants.

Male plants bear only pollen-producing flowers. The sheer magnitude of the stalk and all of that pollen production makes me blush. We spent an hour filming and recording audio of this event the other morning, while watching with rapt attention through binoculars. The best entertainment is often just out our front door!


Females bear thousands of seed-producing flowers (below). Although the bees harvest prodigious amounts of pollen, they do nothing for fertilizing the female flowers because there is no nectar to attract them. The females depend on wind to deliver pollen for fertilization.


The seed and pollen producing catkins look very different side by side. From a distance, you can tell the two types of stalks from one another simply by noticing the presence or absence of insect activity.



Prior to blooming, the catkins emerge from the protective covering of a sheath, waiting for the proper environmental signals, probably a certain minimum temperature, before bursting forth in an orgiastic frenzy.


Meanwhile, in our backyard, a 20 foot tall yucca stalk flowers by the light of a full moon.
What's a woman to do?!?

3 comments:

The Wayward Hawaiian said...

Fascinating! Great photos too! You wouldn't happen to know why some cherries are self-pollinating and others are not, would you? I'm giving the ultimatum to my dwarf cherry. Fruit or else...! Thanks for sharing your knowledge and photos. Snap some photos of those wasps sometime too! -A

Katherine Darrow said...

I'm not in the know about fruit pollination. Do you have other cherry trees around? Many species require cross pollination; just one of those genetic things to avoid inbreeding. So, maybe you need to get the poor tree a partner! :)

Katherine Darrow said...

Also, bees!