COMMON DESCENT

Listen to Episode 125 on PodBean, YouTube, Spotify, or anywhere you can find it!

This one family of plants can be found in nearly every environment on Earth, and yet their deep history is nearly entirely unknown to us. This episode, we discuss the diversity, evolution, and strangeness of Orchids.

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Orchids

Orchidaceae is one of the largest living families of plants, with around 28,000 species spread across every continent except Antarctica, found in nearly every type of biome, and representing as much as 10% of modern seed plants. Their lifestyles are diverse, with many species living “typical” terrestrial lives, while some live atop other plants and some even live underground. Orchids are also extremely common as cultivars. Here in North America (where you humble hosts and blog-writers live), there are over 200 species of orchids, more than half of which are threatened or endangered.

Orchids are flowering plants closely related to many other economically important plants, including onions, garlic, asparagus, and aloe. One of the most unique characteristic features of orchids is the labellum, a large petal that acts as a platform for pollinators while feeding on orchid flowers. Orchid seeds are also notable in being extremely small, often relying on symbiotic relationships with fungi in order to germinate.

Orchids Over Time

Genetic evidence indicates that orchids arose sometime during the Cretaceous Period, perhaps as much as 100 million years ago. Early in their evolution, ancient orchids seem to have undergone a whole genome duplication event, providing the genetic foundations for their later diversity. Some studies indicate that many of the characteristic features of orchids arose early in their evolution, so these plants might have looked familiar to us even many millions of years ago.

Unfortunately, the fossil record of orchids is nearly non-existent. Most orchid remains are known from amber, typically very small fossils (pollen or parts of flowers, for example) preserved alongside insects trapped within the amber. The first definitive orchid leaf fossils were identified from New Zealand in 2009. This paucity of past plants makes it very difficult to understand the evolutionary history of orchids from fossil remains, hence why so much research on their evolution is focused on genetic studies.

Learn more

Zhang et al. 2017. The Apostasia genome and the evolution of orchids (Technical, open-access)

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If you enjoyed this topic and want more like it, check out these related episodes:

• Episode 57 – The Evolution of Flowering Plants (Angiosperms)
• Episode 135 – Seeds
• Episode 38 – Grass
• Episode 73 – Trees

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