Continuing with the series on Australian plants, here are some examples from the Hydatellaceae. Now that the media embargo has lifted, you might be hearing or reading about these in the news over the next few days (I know there is an upcoming BBC radio interview!), thanks to a recent discovery by a UBC Botanical Garden and Centre for Plant Research-led team of researchers with collaborators at the Royal Botanic Gardens in Sydney, Australia, the University of Zurich, Harvard University and the University of California, Davis. UBC researchers involved are Dr. Sean Graham, Jeffery Saarela (now at the Canadian Museum of Nature) and Hardeep Rai (as an incidental aside, my mother taught Jeff's mother in high school). Support for this research was also provided by the UBC Department of Botany.
The team of researchers has a paper being published in the March 15, 2007 edition of Nature, entitled “Hydatellaceae identified as a new branch near the base of the angiosperm phylogenetic tree”. These dwarf aquatic plants found in Australia, New Zealand and India were once thought to be in the order of plants that included the grasses, sedges, bromeliads and rushes (the Poales). Through an incongruous result noted when studying the relationships between early flowering plants, the UBC researchers asked one of the most important questions in science (“Why?”) and decided to investigate further. What they discovered was that the Hydatellaceae are a previously unrecognized ancient lineage of flowering plants – so ancient that they predate the “big split” between the monocots and dicots (or ex-dicots, as is now recognized) in the evolution of flowering plants, and are instead more closely related to the Nymphaeaceae, or water lilies. As Sean states in the UBC press release, “For botanists, this is like finding something you thought was a lizard is actually a living dinosaur.”
Through the generosity of many people, including the people who shared today's photographs (see below), the garden has assembled a web page on the Hydatellaceae with news coverage, more photographs, further reading, links to the researchers and more artwork. I'll be adding more news coverage items and links to journal articles as they become available over the next few days (BBC Radio, Nature podcast, Nature articles, etc.). I imagine Sean might step in here and comment on some of today's photographs as well, though he's been even busier than I've been with this – in the meantime, though, he's written a piece for the Etaerio weblog: A New Understanding of the Early Evolution of Flowering Plants.
Credit and captions for today's photographs are as follows:
A minature turf of Hydatella filamentosa from Dove Lake, Tasmania, where it grows rooted in gravel in the clear water of a mountain lake, down to 75 cm deep. Some Hydatellaceae are annuals and flower above water, but this species is perennial, flowering under water and often forming a dense mat of roots and rhizomes. Voucher B.G. Briggs 9774 (NSW). Photograph © Botanic Gardens Trust, Sydney. Photographer: Simone Cottrell. Used with permission.
Hydatella filamentosa from Dove Lake, Tasmania. The bracts of old inflorescences show among the leaves and rhizomes below the tuft of leaves. The species grows in the clear water of mountain lakes and flowering is under water. The scale is in mm and the plants less than 1.5 cm tall. Voucher B.G. Briggs 9774 (NSW). Photograph © Botanic Gardens Trust, Sydney. Photographer: Simone Cottrell. Used with permission.
Hydatella inconspicua (Hydatellaceae) from Lake Kai Iwi, New Zealand. Photograph © Justin Goh, School of Biological Sciences, University of Auckland, Auckland, New Zealand. Used with permission.
Flowering individuals of Trithuria submersa (Hydatellaceae) from Western Australia, 1998. Each “flower” is a compact head of multiple flowers. Photograph © Dennis Stevenson, New York Botanical Garden. Used with permission.
On a final note, there may or may not be a BPotD for March 15 – depends on how exhausted I am. Then again, there's plenty of information on the Hydatellaceae page to keep you occupied!