Dr. Chips upped the ante in his comment to yesterday's bryophyte blog; he's seen and recognized a hornwort in the field! Take that my fellow naturalists. Only one genus (Anthocercos) is mentioned or illustrated in most textbooks, even ones on plant diversity, but there are 5 more genera, or if you really dwell on minutia, up to eleven genera in all. Basically the problem is that hornworts are small and they tend to grow in wet and very dimly lit conditions, and how often do you go looking around in such places? With a thin, rather irregular ribbony thallus they closely resemble liverworts and the gametophytes of some ferns. The only really distinctive feature readily seen without a microscope is the columnar sporophytes (the "horns"), which are the diploid generation. For the most part these sporophytes are dependent upon the maternal gametophyte, but under certain conditions the sporophyte can persist as a free-growing organism after the maternal gametophyte dies. In terms of complexity, the gametophyte is hardly more complex than some green algae, and indeed it has only 1 chloroplast per cell, a very algal character. So let's get out there, down on your hands and knees, and scout for a new genus to add to your plant diversity life list. Image credit: U. Hawaii.
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2 months ago in Variety of Life
