Tuesday, August 15, 2006



Jurisdynamics' "taxon of the week" feature, interrupted by a wilderness trip, is back. This installment focuses on Ophrys, a genus of orchids characterized by their intriguing relationships with fungi and with insects.

Most Ophrys orchids have symbiotic relationships with fungi. This symbiosis blocks transplantation, to the probable chagrin of those fanatical orchid collectors and orchid thieves who treat family Orchidaceae as palpable playthings. Fungal symbiosis also renders the leaves of some Ophrys species very small and green or bluish in color.

What draws human attention to Ophrys, however, is this genus's distinctive trait of insect mimicry. Consider O. insectifera, the fly orchid. Insectifera's wiry upper petals resemble antennae. Under the false "antennae," two dark patches resemble eyes. The flower's iridescence imitates the effect of light reflecting off wings.

To compound the effect, an Ophrys orchid typically produces a scent that closely resembles the pheromones of a sexually receptive female insect. Of course, the orchid emits this scent precisely at a moment when females remain dormant and only males seek sexual action. The overall effect is irresistible to this male Gorytes mystaceus.

It's called pseudocopulation. It does nothing for the insect. But the orchid benefits.

The orchid's "eyes" are actually waxy globules of pollen. The heavy, sticky nature of orchids' "pollinia" has significant evolutionary consequences. Though some orchids can self-pollinate -- including, notably, O. apifera, the bee orchid -- many rely on visiting insects to transport pollinia on their heads from plant to plant.

Each Ophrys orchid has coevolved with its distinct pollinator insect. Consequently, the orchid depends entirely on that insect for its survival. O. bombyliflora, the bumblebee orchid, depends on its ability to look and smell like female bumblebees so that nearby males are duped into pseudocopulation. Pollinia from one Bombyliflora specimen travel to the stigma of another by sticking to head or the abdomen of a visiting male bumblebee. Similar stories can be told of O. sphegodes, the early spider Orchid; O. fuciflora, the late spider orchid; and O. scolopax, the woodcock orchid.

The upshot? Interaction in nature can be overwhelmingly lopsided. Encounters between taxa need not benefit both sides; as in the case of pseudocopulation, one party loses altogether. Contrary human desires for reciprocity and mutuality are just that, contrary human desires. Hopes of happy symbiosis or at least mutualism, even those expressed on this site, yield in the presence of Ophrys to a more somber assessment of biological interaction.

I tip my hat to my colleague Dan Burk, one of the funniest members of legal academia, for suggesting this taxon of the week.


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