Pine Pods in Amber

Germinating Pine Cone Found Encased in Baltic Amber

Nov 17 2021 Historical Biology, Oregon State University, Professor George Poinar Jr

Seed germination — a crucial stage in the development of all plants — normally occurs in the soil after the seed has fallen from the mother plant. In some infrequent instances, precocious germination — a type of viviparity or vivipary — occurs when the seed sprouts while still within the fruit. In a new paper published in the journal Historical Biology, Oregon State University’s Professor George Poinar Jr. described the first case of precocious germination of a fossil plant involving a number of seeds that have germinated in a pinecone embedded in a piece of 40-million-year-old (Eocene epoch) Baltic amber.

“Crucial to the development of all plants, seed germination typically occurs in the ground after a seed has fallen,” Professor Poinar said. “We tend to associate viviparity — embryonic development while still inside the parent — with animals and forget that it does sometimes occur in plants. Most typically, by far, those occurrences involve angiosperms.”

The pinecone derives from the Eocene Epoch, which lasted from 56 million to 33.9 million years ago.

During this time, climates were warm and humid and temperate and subtropical forests were widespread.

However, grasslands did not flourish throughout the world as they did in later time periods.

The earliest Eocene Epoch mammals were all small, but larger species evolved toward the end of the epoch. Early bats, rabbits, beavers, rates and carnivore mammals roamed the Earth, along with the first appearance of the cetaceans, which includes whales and dolphins.

The frozen scene depicted above shows the pinecone sprouting seeds that produced embryonic stems, which is a process known as precocious germination and typically only found among fruits like tomatoes and grapefruit (Think of the little orange inside of the big orange you just peeled for snacking.)

The amber-encased pinecone comes from the extinct pine species Pinus cembrifolia (thought to be the main source or one of the main sources of amber.)

'In the case of seed viviparity in this fossil, the seeds produced embryonic stems that are quite evident in the amber,' Poinar said. 'Whether those stems, known as hypocotyls, appeared before the cone became encased in amber is unclear. 'However, based on their position, it appears that some growth, if not most, occurred after the pinecone fell into the resin.'

Poinar continued to explain that 'some activity does happen after a creature or plant becomes encased in the ancient tree resin.'

Previous discoveries have produced cases of insects laying eggs or parasites attempting to escape from a host. In the case of the pinecone, the cuticle covering the exposed portions of the shoots could have protected them from rapid entrance of the resin's natural fixatives,' said Poinar.

Research on viviparity in extant gymnosperms suggests the condition could be linked to winter frosts. Light frosts would have been possible if the Baltic amber forest had a humid, warm-temperate environment as has been posited, Poinar said. 'This is the first fossil record of seed viviparity in plants but this condition probably occurred quite a bit earlier than this Eocene record,' he said. 'There's no reason why vegetative viviparity couldn't have occurred hundreds of millions of years ago in ancient spore-bearing plants like ferns and lycopods.'

Just a few notes by Andzia Chmil Stout

I had to look up a few words and their definitions while reading Professor Poinar Jr's paper. The first word was viviparity---the condition of the offspring developing inside of the parent---just like us! The next word I searched for was angiosperm---which covers a lot of ground---such as trees, plants, grasses, etc. Angiosperms bear fruit/flowers/blossoms and pollen. We have to give angiosperms a great big thank you as they provide wood for shelter, paper for writing, fiber for clothing along with medicines. They also give us much joy by the taste, smell, texture and sight of fruit and flowers full of scents and beauty.

I also looked up the meaning of hypocotyls---and while Prof Poinar Jr does a good upfront job of explaining them in reference to the pinecone in amber---'In the case of seed viviparity in this fossil, the seeds produced embryonic stems that are quite evident in the amber,' Poinar said. I checked the word out a little further and found out that it is the stem of the embryo beneath the stalks of the seed leaves.

Not sure what your takeaway is from this brief paper, but it opened up a new world for me. The very idea of a pinecone sending out seeds from its body to ensure survival of its species while trapped in amber is both beautiful and poignant. Long before we humans appeared on the scene, the DNA from the pine trees was already doing its thing. And here we are, some eons and eons later, sharing 50 per cent of our DNA with the trees. So, the next time you feel like hugging a tree-go right ahead! Chances are you are wrapping your arms around an old family member who just might hug you back!

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