Tuesday, July 8, 2008

Amorphophallus Update, July 8

70.5 inches (179 cm) tall, 1.5 inches taller than yesterday.

Something I hadn't really thought about, until a visitor to the greenhouse during the 2004 Corpse Flower event pointed it out, is that the inflorescences of Amorphophallus are asymmetrical, and can be either right or left handed. That is to say, the spathe wraps around the axis of the bloom, and at the seam either overlaps itself towards the right side (viewer's right, as seen in this photo), or overlaps itself towards the left side. All of the Corpse Flower blooms at UConn (four of them, from two individuals) have been right handed, but left handed blooms do occur, as well. For example, the Smith College 2005 inflorescence and this one at Kew were left handed.

Inspection of the Amorphophallus bulbifer flowers that I posted a photo of last week shows one right handed and one left handed plant in the same pot. These inflorescences are borne on separate corms, but the corms are almost certainly clones of each other, and genetically identical (A. bulbifer reproduces prolifically from offsets, and bulbils that grow from the leaves). So it is likely that handedness is not determined genetically, for at least some Amorphophallus species. I wonder if plants can switch back and forth from year to year? In any event, handedness in Amorphophallus inflorescences seems to be a morphological oddity of little or no biological significance; development proceeds either one way or the other, and there's no functional difference in the end.

Some other instances of handedness in asymmetrical flowers are important for pollination biology. For example, in enantiostylous (Amorphophallus is "enantiospathous" ^_^) flowers, handedness differences probably function to prevent self pollination and encourage outcrossing.

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