Podd Post - 05/06/03 08:05 PM
Hello, everyone.
Asparagus was the topic of an old thread. As to "pod," a stretch for vanilla beans.
From today's New York Times:
May 6, 2003
An Orchid by Any Other Name: An Asparagus?
By CAROL KAESUK YOON
Orchids can be elegant, gaudy, lurid and even downright bizarre. But while the unusual flowers of these species have excited plant lovers for centuries, they have also made it difficult for evolutionary biologists to place them in the plant family tree and identify their closest relatives.
But now, scientists say, studies of the DNA of orchids are revealing a host of surprises, chief among them, that orchids are actually part of the asparagus group, closer kin to these vegetables than to the other, flashier, flowering plants they had been placed with before.
"They're so weird, so different from everything else," said Dr. Ken Cameron, orchidologist at the New York Botanical Garden in the Bronx.
At the same time, scientists are finding that orchids, long thought to be the recent product of plant evolution, are actually quite ancient, having emerged more than 90 million years ago.
It is often easy for experts to pick out an organism's closest relatives, but sometimes ? as with orchids ? appearances can point in many directions and no direction at all.
One problem is that orchid flowers have undergone striking evolutionary elaborations, evolving myriad forms and devices, sometimes to entice very particular animal pollinators. In the process, elements of flower structure that may have pointed to the group's evolutionary history have been distorted or lost.
One particular oddity of orchid flowers is their highly unusual reproductive structure, the normally separate array of reproductive parts having evolved to be fused together inside a typical orchid bloom.
"You look inside an orchid, and say, `Where are all the parts?' " said Dr. Cameron. "It doesn't look like anything else."
By looking at DNA, researchers were able to free themselves from limits of vision. Comparing instead a wide variety of genes both among the orchids and between orchids and the other flowering plants, Dr. Cameron and colleagues found that the orchids fell squarely within the so-called Asparagales, the group that includes asparagus.
"People found it hard to believe," Dr. Cameron said. But the Asparagales is large and diverse, containing amaryllis, onions, irises, daffodils as well as agaves and yuccas.
Scientists say the evolutionary history of orchids has also been obscured by the oddities of their pollen. While the pollen of most plants is nearly indestructible, the pollen of orchids is typically extremely delicate, leaving no fossil record.
"With other groups you can find a fossil and conclude that the group must be at least that old or older," said Dr. Mark Whitten, a botanist at the Florida Museum of Natural History. "But with orchids it's been pretty much sheer speculation."
Now, when DNA data are used to build an evolutionary tree of the plants, they show that orchids branch off fairly early, the first among the Asparagales plants, meaning they are the oldest in that group.
Orchids also branch off before the palms. Because there are palm fossils that are 90 million years old, scientists know, orchids must be at least that old. The same evolutionary trees also showed that orchids first lived on the ground, and later evolved to live on other plants, as most orchids do, suggesting that life in the trees, a less exploited habitat, might have helped orchids diversify into so many species.
But while DNA has provided these answers, Dr. Cameron said, researchers may have had clues to the history of the orchids if they had not focused so much on the showy and high profile orchid species.
One curious aspect of the Asparagales is that their seeds are encased by a distinctive black, crusty coat.
Because most orchids have very thin seed coats, the Asparagales seemed unlikely to be close relatives. Yet Dr. Cameron has found that some of the more obscure orchids have exactly the Asparagales sort of seed. He noted that Neuwiedia, an unusual Bornean orchid, lady-slipper orchids and vanilla orchids, which produce the vanilla used in cooking, also have these seeds.
In fact, Dr. Cameron points out that the tiny black specks seen in some vanilla ice creams, are, in fact, those crusty black-coated seeds that show the clear alliance of the orchids with asparagus, meaning that the answer to a longstanding scientific puzzle has long been right on the tip of people's tongues.
Copyright 2003 The New York Times Company
Asparagus was the topic of an old thread. As to "pod," a stretch for vanilla beans.
From today's New York Times:
May 6, 2003
An Orchid by Any Other Name: An Asparagus?
By CAROL KAESUK YOON
Orchids can be elegant, gaudy, lurid and even downright bizarre. But while the unusual flowers of these species have excited plant lovers for centuries, they have also made it difficult for evolutionary biologists to place them in the plant family tree and identify their closest relatives.
But now, scientists say, studies of the DNA of orchids are revealing a host of surprises, chief among them, that orchids are actually part of the asparagus group, closer kin to these vegetables than to the other, flashier, flowering plants they had been placed with before.
"They're so weird, so different from everything else," said Dr. Ken Cameron, orchidologist at the New York Botanical Garden in the Bronx.
At the same time, scientists are finding that orchids, long thought to be the recent product of plant evolution, are actually quite ancient, having emerged more than 90 million years ago.
It is often easy for experts to pick out an organism's closest relatives, but sometimes ? as with orchids ? appearances can point in many directions and no direction at all.
One problem is that orchid flowers have undergone striking evolutionary elaborations, evolving myriad forms and devices, sometimes to entice very particular animal pollinators. In the process, elements of flower structure that may have pointed to the group's evolutionary history have been distorted or lost.
One particular oddity of orchid flowers is their highly unusual reproductive structure, the normally separate array of reproductive parts having evolved to be fused together inside a typical orchid bloom.
"You look inside an orchid, and say, `Where are all the parts?' " said Dr. Cameron. "It doesn't look like anything else."
By looking at DNA, researchers were able to free themselves from limits of vision. Comparing instead a wide variety of genes both among the orchids and between orchids and the other flowering plants, Dr. Cameron and colleagues found that the orchids fell squarely within the so-called Asparagales, the group that includes asparagus.
"People found it hard to believe," Dr. Cameron said. But the Asparagales is large and diverse, containing amaryllis, onions, irises, daffodils as well as agaves and yuccas.
Scientists say the evolutionary history of orchids has also been obscured by the oddities of their pollen. While the pollen of most plants is nearly indestructible, the pollen of orchids is typically extremely delicate, leaving no fossil record.
"With other groups you can find a fossil and conclude that the group must be at least that old or older," said Dr. Mark Whitten, a botanist at the Florida Museum of Natural History. "But with orchids it's been pretty much sheer speculation."
Now, when DNA data are used to build an evolutionary tree of the plants, they show that orchids branch off fairly early, the first among the Asparagales plants, meaning they are the oldest in that group.
Orchids also branch off before the palms. Because there are palm fossils that are 90 million years old, scientists know, orchids must be at least that old. The same evolutionary trees also showed that orchids first lived on the ground, and later evolved to live on other plants, as most orchids do, suggesting that life in the trees, a less exploited habitat, might have helped orchids diversify into so many species.
But while DNA has provided these answers, Dr. Cameron said, researchers may have had clues to the history of the orchids if they had not focused so much on the showy and high profile orchid species.
One curious aspect of the Asparagales is that their seeds are encased by a distinctive black, crusty coat.
Because most orchids have very thin seed coats, the Asparagales seemed unlikely to be close relatives. Yet Dr. Cameron has found that some of the more obscure orchids have exactly the Asparagales sort of seed. He noted that Neuwiedia, an unusual Bornean orchid, lady-slipper orchids and vanilla orchids, which produce the vanilla used in cooking, also have these seeds.
In fact, Dr. Cameron points out that the tiny black specks seen in some vanilla ice creams, are, in fact, those crusty black-coated seeds that show the clear alliance of the orchids with asparagus, meaning that the answer to a longstanding scientific puzzle has long been right on the tip of people's tongues.
Copyright 2003 The New York Times Company
