Sunday, May 22, 2011

It's Not Easy Being Green, Or Is It?

I recently came across a population of one of our more common orchids, Habenaria repens, in a wet ditch in the Orlando area. Known by the common name of 'Water Spider Orchid', plants are notoriously difficult to see even when in full flower, owing to the fact that the plant, along with its minuscule flowers (which are a bit over 1 cm wide), is completely green to yellow-green.

This might cause you to wonder, "How on earth would a completely green flower stand out enough from its background vegetation to be seen by a pollinator?" Just FYI, these flowers are not self-pollinating. It's easy enough to see a flash of pink, red, purple, blue, or buttery yellow against the sea of background vegetation and hone in on the location of a flower, even from a fair distance, but green just blends in with all the other greens that you see. The answer is that it's all a matter of timing.

Walk by the same roadside ditch at night and the flowers will be even less observable by the sense of sight. But even our ridiculously dull sense of smell will pick up a distinct, sweet fragrance wafting over the shallow water. A night flying moth, with a much stronger sense of smell, will be able to find these flowers from miles away, provided that it is not misled by all of our 'artificial moons' (electric lights of various kinds) that interfere with its sense of lunar navigation. Following this stream of sweet odor, these vampires of the Lepidoptera make their way to their quarry. Inserting their probosces into the spur-like nectary that is formed by the back of the lip, they drink sweet nectar from the last few millimeters at the end of the spur. This reward is not, however, offered without its price. The eyes of the insects engage the tips of the pollen-bearing structures (known as pollinia) which are coated with a sticky glue. Thus, when the insect withdraws, its eyes now bear the pollinia to carry them to the next flower. It's a dance between insect and flower that goes largely unobserved, unless you happen to shine a flashlight on a flowering stem at just the right moment.

This strategy of night-scented orchids is actually pretty common in Florida, although not all of them are green-flowered. Some flowers are brilliant white, which might make them more observable in the dim starlight or moonlight that reaches the inner recesses of the forests and swamps where many of these species make their homes. Here is a list of Floridian orchids that are known to be night-scented:

  • Dendrophylax lindenii
  • Dendrophylax porrectus
  • Epidendrum amphistomum
  • Epidendrum floridense
  • Epidendrum magnoliae
  • Epidendrum nocturnum
  • Habenaria macroceratitis
  • Habenaria odontopetala
  • Habenaria quinqueseta
  • Habenaria repens
  • Tipularia discolor
And here is a list of species that are likely night-scented as well, extrapolating from their inconspicuously colored flowers:
  • Epidendrum rigidum
  • Epidendrum strobiliferum
  • Habenaria distans
  • Platanthera flava
  • Platanthera clavellata
I would be interested to hear about anyone's experience around these species, whether or not they have a night fragrance as well.

Sunday, May 15, 2011

Flowers of Early Summer

May in many areas of the northern hemisphere would be considered late spring. In central and southern Florida, it is decidedly summer-like already with temperatures in the 90s and a blazing sun that will burn your skin in a matter of minutes. Here are a few flowers that you might encounter in Florida at this time. It is by no means an exhaustive list, as many more species are in flower than just fact, at any time of the year in Florida, as many as 40 species might be in flower somewhere in our wild areas. Click each thumbnail to go to the full profile page for the species on my website.

Grass Pink (Calopogon tuberosus)
Grass Pink Profile Page

Scarlet Ladies Tresses (Sacoila lanceolata)
Scarlet Ladies Tresses Profile Page

Florida Dancing Lady Orchid (Tolumnia bahamensis)
Florida Dancing Lady Orchid Profile Page

Water Spider Orchid (Habenaria repens)
Water Spider Orchid Profile Page

Spring Ladies Tresses (Spiranthes vernalis)
Spring Ladies Tresses Profile Page

Rose Pogonia (Pogonia ophioglossoides)
Rose Pogonia Profile Page

Florida Butterfly Orchid (Encyclia tampensis)
Florida Butterfly Orchid Profile Page

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