Three plus one equals four, but the flowers of trailing four o’clocks are three in one

On my way along the Apache Trail from Phoenix to Canyon Lake on September 29th, I couldn’t help noticing ground-hugging colonies of magenta flowers by the side of the road (see the first photo, which looks mostly downward). Thanks to George Miller of the Native Plant Society of New Mexico, I now know that these are trailing four o-clocks, Allonia incarnata. Here’s a closer look at one of the flowers.

The scientific name of this wildflower teaches us that plants in the genus Mirabilis aren’t the only ones that people have called four o’clocks (even if some wildflowers in that genus go by other popular names as well, like the angel’s trumpet you recently saw). I’ve learned that the genus Allonia includes just two species, and that what appears to be a single flower is actually three flowers; the six lobes in the upper right of the close-up photo delineate one of those flowers, and you can count six lobes clockwise and counterclockwise from that flower to see the other two  flowers that complete this triune inflorescece. That just gave me an idea for what I would call an inflorescent bulb: turn on the power and out comes a flower. Of course some bulbs already give rise to flowers, just not at the speed of light. Oh well, flights of fancy aside, you’re welcome to read a down-to-earth Wikipedia article about the two-species Allonia genus.

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This is another entry from the saw (as in the past tense of see) part of the see-saw that’s been oscillating between pictures from my trip to the American Southwest in late September and more-recent pictures showing what’s been going on in Austin.

© 2014 Steven Schwartzman

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