Fossilized Flower Places Angiosperms in the Jurassic

1, style branches; 2, dendroid style; 3, sepal; 4, ovarian roof; 5, scale; 6, seed; 7, cup-form receptacle/ovary; 8, bract; 9, petal; 10, unknown organ (staminode?).  [SOURCE]

1, style branches; 2, dendroid style; 3, sepal; 4, ovarian roof; 5, scale; 6, seed; 7, cup-form receptacle/ovary; 8, bract; 9, petal; 10, unknown organ (staminode?). [SOURCE]

Despite their dominance on the landscape today, the origin of flowering plants is shrouded in mystery. The odds of any living material becoming fossilized is extremely rare and when you consider the delicate and ephemeral nature of most flowers, one can begin to understand why their fossils are so special. The last few decades have seen tantalizing evidence emerge from fossil beds dating to the Cretaceous Period but a recent set of fossils from China predate the oldest confirmed angiosperm fossils by 50 million years. That’s right, it would appear that flowering plants were already on the scene by the early Jurassic!

The fossils in question have been coined Nanjinganthus dendrostyla. They were discovered in China in a formation that dates back roughly 174 million years. To most of us they look like a bunch of dark, albeit elaborate smudges on the rocks. To a trained eye, however, these smudges reveal intricate anatomical details. Amazingly, the team of paleobotanists responsible for this discovery had a lot of material to work with. Descriptions were made on a whopping 264 specimens representing 198 individual flowers. This amount of data means that the declaration of angiosperm affinity stands on pretty solid ground.

A single  Nanjinganthus  flower  [SOURCE]

A single Nanjinganthus flower [SOURCE]

Aside from their age, there is a lot about these fossils that surprised researchers. Probably the biggest surprise is their overall appearance. Paleobotanists have long hypothesized that early angiosperm flowers likely resembled something akin to a modern day Magnolia and invoke floral features such as apocarpy, a superior ovary, and a lack of an obvious style as likely features to look for in ancient plant fossils. Surprisingly, Nanjinganthus does not seem to conform to many of these expectations.

One of the most striking features of these fossils are the styles. They are large and branched like tiny trees (hence the specific epithet “dendrostyla”). The tree-like appearance of the style suggests that early angiosperms likely did not rely on insects for pollination. The branches themselves greatly increase the amount of surface area available for pollen capture, which could mean that Nanjinganthus was wind pollinated.

Flowers of  Nanjinganthus  preserved in different states and their details. For specific details on each image, please see   SOURCE

Flowers of Nanjinganthus preserved in different states and their details. For specific details on each image, please see SOURCE

Another surprising feature is the presence of an inferior ovary that, by its very definition, sits below the sepals and petals. It has long been hypothesized that early angiosperms would exhibit superior ovaries so this discovery means that we must rethink our expectations of how flowers evolved. For instance, it suggests we may not be able to make broad inferences on the past based on what we see in extant angiosperm lineages. It could also suggest that the origin of flowering plants was not a single event but rather a series of individual occurrences. It could also be the case that the origin of flowering plants occurred much earlier than the Jurassic and that Nanjinganthus represents one of many derived forms. Only further study and more fossils can help us answer such questions.

Another way in which Nanjinganthus deviates from theoretical expectations is in the presence of both sepals and petals. Up until now, paleobotanists have been fond of the idea that petals arose much later in angiosperms, having evolved over time as leaves became more and more specialized for attracting pollinators. The fact that Nanjinganthus was likely wind pollinated yet had both sepals and petals is a bit of a conundrum and further emphasizes the need to revisit some of our long-held assumptions of flowering plant evolution.

Details of the sepal and petal as seen through different forms of microscopic analysis. For specific details on each image, please see  SOURCE .

Details of the sepal and petal as seen through different forms of microscopic analysis. For specific details on each image, please see SOURCE.

By far the most important feature present in these fossils are the ovaries. For any fossil to unequivocally qualify as an angiosperm, it must have seeds encased in an ovary. This, after all, is the main feature that separates angiosperms from gymnosperms. Indeed, Nanjinganthus does appear to fit this definition. Thanks to the sheer amount of fossils available for study, the team discovered that the seeds of Nanjinganthus were enclosed in a cup-like chamber that was sealed off from the outside world by a structure they refer to as an “ovarian roof.” This roof does not appear to have any sort of opening, which worked out quite nicely for paleobotanists as it prevented sediments from entering into the chamber, thus preserving the seeds or ovules (it is hard to tell where they were in the developmental process) for study. This feature more than all others secures its identity as a flowering plant.

Based on the sediments in which these flowers were fossilized, it appears that this plant grew close to water. Also, despite its abundance in this particular fossil layer, it very likely was not a common component of this Jurassic landscape. In reality we still have a lot to learn about Nanjinganthus. What we can say with some certainty at this point is that the presence of Nanjinganthus in the early Jurassic likely means that flowering plants arose even earlier. Nanjinganthus is most definitely not the first flower. We will probably never find the first of anything. It is an ancient flower though, predating all other discoveries by at least 50 million years. This is why paleontology is so incredible. Who knows what the next blow of a rock hammer will turn up!

 

EDIT (10/27/2018): Since writing this post it has come to my attention that there is quite a bit of controversy attached to the description of this fossil. Many have reached out informing me that these fossils may actually be a gymnosperm organ rather than a flower. Despite all of the outcry I have yet to see any published critiques on this particular controversy. I anxiously await more professional input on the subject but for now I have decided to keep the content of the original piece as is. Of course extraordinary claims require extraordinary evidence and not being a paleobotanist myself, I cannot trust hearsay on the internet as fact, no matter how vociferous, until I see it published in a peer reviewed outlet of some sort. Please stay tuned as this story develops! 

Photo Credits: [1]

Further Reading: [1]

A Cave Dwelling Nettle From China

Caves and plants do not seem like a good combo. Plants need sunlight and caves offer very little to none of it. However, plants in general never seem to read the literature we write about them. As such, they are constantly surprising botanists all over the world. 

A recent example of this was published back in September of 2012. A team of botanists exploring limestone gorges in southwestern China stumbled upon three new members of the nettle family. One of these nettles seemed to be right at home growing well within two limestone caves. 

Needless to say this was quite a shock to the botanists. The regions in which these plants were growing were quite dim, with light levels ranging from a mere 0.04% to a measly 2.78 % of full daylight! Although this is by no means complete darkness, it is an incredibly low amount of sunlight for a plant that still relies on photosynthesis to get by. 

They named the nettle Pilea cavernicola in reference to its cave-dwelling habit. While it has only just been discovered, the IUCN considers this species vulnerable. Only two populations are known and their proximity to expanding human activity puts them in danger of rapid extinction. 

Photo Credit: Monro & Wei

Further Reading: [1]

The Corybas Orchids

Today I want to introduce you to the wild miniature world of the helmet orchids (genus Corybas). These little marvels of evolution are native to Australia, New Zealand, New Guinea, southeast Asia, the Himalayas, southern China, a handful of Pacific islands, and a few sub-Antarctic islands as well. They are a poorly understood genus and at least a handful of species are threatened by habitat destruction and poaching. If you are looking at these and thinking "I want one!" please do your homework and make sure that you are purchasing nursery grown specimens.

Photo Credits: kavanaru (http://bit.ly/1TtoBuq), cvh-news CVH新闻 (http://bit.ly/1VqTb5G), Orchi (Wikimedia Commons), Michael Whitehead (Wikimedia Commons), chipmunk_1 (Wikimedia Commons), Boaz Ng (http://bit.ly/1LwfmSp), Jon Sullivan (http://bit.ly/1SVfjrg), and Lucas Arrrrgh (http://bit.ly/24dlytW)

Further Reading:
http://www.iucnredlist.org/details/44392794/0

http://www.iucnredlist.org/details/22486395/0

http://orchids.chookman.id.au/corybas/corybas.html

Plight of the Panda: a bamboo story

There are few creatures more iconic than the giant panda. These bears are the poster children for conservation movements around the world. Unlike their ursine relatives, pandas have abandoned carnivory for a diet that consists almost entirely of bamboo. In the light of human destruction, specialist lifestyles like the pandas are a risky strategy. It doesn't take much to upset such obligate relationships and humans are quite proficient at doing just that. However, the plight of the giant panda has just as much to do with the ecology of its food source as it does man-made destruction of its habitat.

Essentially giant grasses, the bamboo tribe consists of over 1,400 species worldwide. Not only are bamboo some of the tallest grasses in the world, they are also some of the fastest growing plants. Some have been known to grow 250 cm (90 in) in only 24 hours! As typical with grasses, bamboo can reproduce via underground rhizomes, forming dense stands of clones. Entire forests can be made up of the clones of only a few individuals.

The strangest part of bamboo ecology is that they rarely flower. A typical bamboo will live for 20 to 60 years before flowering, with some species taking well over 100 years. As such, bamboo experiences mast flowering events, with entire bamboo forests flowering all at once. After flowering and setting seed, the bamboo dies. Entire bamboo forests are lost in only a matter of weeks.

There have been many hypotheses put forth to explain this and while each has likely played a role in the evolution of this strategy, these mast flowering and subsequent death of bamboo forests probably serve to ensure the survival of the next generation. If the adults were to live through flowering and seed set, it is likely that the thick canopy of the parents would be too much for young seedlings to overcome. What's more, mass die offs create a significant fuel load for fires to sweep through. However catastrophic a fire may be, it reduces competition for bamboo seedlings.

Before humans fragmented their habitat, giant pandas had no trouble dealing with mass bamboo die offs. They simply migrated to a new bamboo forest. Anymore today, they cannot do that. When a bamboo forest flowers and dies, pandas in that area have nowhere to go. They simply starve to death. Because of this, pandas now occupy a mere fraction of their former range. What intact bamboo forests remain are restricted to the highlands of the Sichuan, Shaanxi, and Gansu provinces.

Despite considerable success in the captive breeding of pandas, there is simply not enough habitat to support their recovery in the wild. Because of this, captive breeding programs have come under harsh criticism. It has been argued that the massive amounts of money spent on captive breeding of pandas could be spent on habitat conservation projects elsewhere. No matter where you stand on the subject, there is no denying that pandas fall under the charismatic megafauna syndrome. They captivate the hearts and minds of people all over the globe. They also encourage the masses to open up their wallets. Sadly, it is probably too late giant pandas in the wild. If anything else, they certainly serve as a stark reminder of the importance of habitat conservation on a large scale.

Photo Credit: Abby Wood, Smithsonian's National Zoo (http://bit.ly/1qDX21K) and Daniel J. Layton (Wikimedia Commons)

Further Reading:

http://www.jstor.org/stable/10.1086/303243?seq=1#page_scan_tab_contents

http://www.completebamboo.com/bamboo_behaviors.html

Primitive Orchids

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The genera Neuwiedia and Apostasia represent something quite interesting. What you are looking at here are believed to be two of the most primitive extant orchid lineages. Unlike most orchids, which have a single fertile stamen fused with a single pistil, these genera have 3 and 2 fertile stamens respectively. Though botanists hesitate to consider these genera ancestral to all other orchid lineages, they nonetheless feel that they represent a very primitive sister-group to other basal orchid lineages such as the cypripediads. They can be found in parts of China, India, Sri Lanka, Southeast Asia, New Guinea, and Queensland, with Neuwiedia having the smallest distribution. 

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Photo Credit: Rachmat Setiawan Saleh (http://bit.ly/Zuy37j), Johannes Lundberg (http://bit.ly/1ydRIah), and chipmunk1 (http://bit.ly/1sjMJTh)

Further Reading: 

http://onlinelibrary.wiley.com/doi/10.1111/j.1095-8339.1993.tb00331.x/abstract

A Plant That Isn't

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Every once in a while a story so silly makes it through some of the larger news organizations that it just makes you want to slap your forehead so hard that you knock yourself out. A few years back a story broke and spread like wildfire. Apparently a Chinese nun discovered a legendary Buddhist flower growing under her washing machine. The story took the world by storm. Everyone seemed to be talking about it. But just as quickly as it came, it was gone, which was probably for the better. These Buddhist flowers are referred to as "Udumbara" and there are a lot of historical references to them throughout religious texts. However, like aliens, Bigfoot, and the Loch Ness Monster, from time to time these pseudo-scientific trends get out of hand.

There are so many botany fails when it comes to the idea of Udumbara that you really wonder what kind of reality some people exist in. For starters, Udumbara is said to only bloom once every 3,000 years. Oh really? Who keeps track of these events? Evolutionarily speaking, what could possibly be the benefit to a strategy like this? Second, every supposed picture of an Udumbara depicts a plant with no chlorophyll and no roots. They seem to grow on some pretty strange surfaces as well. Whereas there are many examples of achlorophyllous plants in nature, they are still readily recognizable as plants. Also, they all have intricate and specific adaptations to be able to live this way. Some tap into the roots of a host plant while others steal nutrients from mycorhizzal fungi. Okay, so perhaps the latter is what Udumbara does... Not so fast. The extreme differences in the supposed locations that they are found would seem to suggest that a possible fungal symbiont is quite a generalist. If that is the case, why aren't Udumbara more common? Finally, if the discoverers of these "plants" are so adamant about their existence then why have none ever made it into the hands of a competent botanist for a more thorough study?

There are numerous blog posts claiming that the denial of the existence of the Udumbara flower is some sort of mass botanical cover-up conspiracy (yea, such a thought exists). There are plenty of others that claim "irrefutable proof" via macro shots of some blurry structures which, to the authors, seem to show actual floral anatomy. Though I am not writing this post to bash on religious beliefs, I am making an attempt to attack the perpetuation of pseudo-scientific dogmas that are still painfully abundant in otherwise modern times. The real explanation for Udumbara is most likely lacewing eggs. Lacewings lay their eggs on the ends of long strands of silk to help hide them from predators like ants. Many of the reported pictures of Udumbara flowers depict exactly that. Other pictures depict what more closely resembles the fruiting bodies of some slime molds which take up that morphology once they mature.

As far as I am concerned I have yet to see anything remotely convincing that these Udumbara "flowers" are anything other than lacewing eggs or slime mold. To claim that the botanical community is conspiring against the true identity of these "flowers" is to be completely naive to how botanists tick. To think that any botanist would turn down an opportunity to admire and study a plant previously unknown to science is just plain silly. The internet can be such a wonderful tool for research and broadening horizons but it is also a cesspool of misinformation and one wrong turn can send you spiraling into the realm of crazy. Be careful of where you get your information. It's okay to be open minded but don't be so open minded that your brain falls out. Question everything and embrace the discipline that is scientific thought and reasoning.

Photo Credit: Be Zen

Further Reading: http://naturelap.wordpress.com/2010/03/04/udumbara-flower-that-blooms-every-3000-years/

http://www.theepochtimes.com/n2/science/udumbara-blossoms-buddhist-celestial-31484.html

http://www.telegraph.co.uk/news/worldnews/asia/china/7345137/Rare-Buddhist-flower-found-under-nuns-washing-machine.html