Oenothera rhombipetala

And another entry written by Taisha Mitchell today:

Oenothera rhombipetala, or the diamond-petal evening primrose, is photographed here by Don McClane@Flickr. He photographed this in mid-July of last year near Sedgwick County Park in Wichita, Kansas, USA. Thanks Don!

Also known as the four-point evening primrose, this species is found throughout much of the central continental USA. Like many members of the genus, Oenothera rhombipetala has a biennial life-cycle: in the first year, the germinated seed produces a rosette of leaves. In the second year, an erect leafy stem bearing flowers grows. Opening in the evening, the yellow flowers with their 4 distinctly-pointed petals wither the following morning.

It was observed in the 1960s that Oenothera rhombipetala seemed to be the single pollen source-food for the nocturnal bee species Sphecodogastra texana (flowering can occur all summer long, provided there is enough moisture). More recently, research by R. J. McGinley has shown that female bees of this genus collect pollen almost exclusively from members of the Onagraceae. Onagraceous pollen is unusually-shaped and enveloped in viscin (sticky) threads. Female Sphecodogastra bees have specialized curved pollen-collecting hairs on their hind legs, which allows them to accumulate large loads of the sticky pollen (see: McGinley, R.J. 2003. Studies of Halictinae (Apoidea: Halictidae), II: Revision of Sphecodogastra Ashmead, floral specialists of Onagraceae. (PDF) Smithsonian Contribution to Zoology 610).

Oenothera rhombipetala

4 responses to “Oenothera rhombipetala”

  1. Diogenes

    Did the location somehow disappear from the label portion of the posting? I rely on it to tell me whether I should continue drooling (and trying to locate said plant for my garden) or whether just to enjoy the photo and label it “in my dreams.” Thanks!

  2. Stuart

    I’m really enjoying the entries written by Taisha. Very good job!
    This has sparked my curiosity about the nocturnal bee species Sphecodogastra texana. I always thought bees navigated by using the position of the sun. How can they find their way in the dark?

  3. Connie Hoge

    I, too, enjoy Taisha’s work.
    Honeybees use the sun. Solitary bees probably don’t.

  4. Daniel Mosquin

    Diogenes, my fault on this one — I neglected to include that. For a few of the previous entries, we were not given the location, so it is admittedly vague.

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