Rosa Rubicondior: Unintelligent Design - The Needless Complexity That Produces Orchids

Thursday, 9 October 2025

Unintelligent Design - The Needless Complexity That Produces Orchids

Cremastra variabilis

Deadwood brings wild orchids to life | Kobe University News site

An interesting open-access paper, recently published in the journal, Functional Ecology, by two researchers from Kobe University, Japan, explains the complex, symbiotic relationship between an orchid and a wood-decomposing fungus, not only between the fungi and the adult plants that depend on the fungi to provide the orchid with nutrients, but also for the orchid seed to germinate.

This complex relationship appears to benefit the orchid because it can live in otherwise nutrient-poor conditions. However, from an intelligent design perspective, it makes no sense at all because an omnipotent, omniscient designer could have endowed the orchid with the genetic machinery to do what the fungus does.

The relationship between the seeds and the fungus is even more bizarre. The seeds, unlike those of other plants, are devoid of nutrients and therefore need the fungus to supply some. Orchid seeds are notoriously small, being almost invisible to the naked eye. Contrary to Jesus’s bizarre reputed claim in the Bible that the mustard seed is the smallest seed, orchid seeds are orders of magnitude smaller.

Another parable put he forth unto them, saying, The kingdom of heaven is like to a grain of mustard seed, which a man took, and sowed in his field: Which indeed is the least of all seeds: but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof.

Matthew 13: 31–32

The mustard seed is not only not the smallest of seeds but also doesn’t grow into a tree!

Contrary to what creationists have been conditioned to believe, one of the hallmarks of good, intelligent design is minimal complexity because the simpler a process is, the fewer opportunities there are for it to go wrong.

The converse is true for evolved organisms and processes because there is no plan or foresight in evolution, which can only build on what is already present, and natural selection prioritises utility, based solely on what is better than what preceded it. Consequently, evolved organisms are a collection of suboptimal compromises, and there is selection pressure to minimise failures with another layer of complexity.

This has led to confusion in creationist thinking, which associates complexity with intelligent design as they try to force-fit what can be observed with their need to have a role for their particular deity — especially in their own ‘design’ — giving them a sense of importance that being ‘merely’ the product of evolution doesn’t give them.

Evolution of Orchids and Their Fungal Partners. Orchids — members of the vast and diverse family Orchidaceae — are believed to have evolved between 76 and 84 million years ago, during the Late Cretaceous. Molecular clock studies suggest they were already diversifying before the extinction of the dinosaurs, and fossil evidence from the Eocene confirms their presence tens of millions of years ago.

Unlike most flowering plants, orchid seeds are extremely small and lack endosperm — the nutrient-rich tissue that typically fuels germination. To survive, they rely on mycorrhizal fungi (often species of Tulasnella, Ceratobasidium or Sebacina) to provide sugars, amino acids and other essential nutrients during the earliest stages of development. This process, called mycoheterotrophy, is crucial for germination and early growth.

Over evolutionary time, this dependency has profoundly shaped orchid biology and ecology:

Seed evolution: By shedding the energy cost of producing endosperm, orchids can produce millions of tiny seeds, improving dispersal and colonisation potential.
Fungal partnerships: Orchids form highly specific relationships with particular fungal partners, though some species can associate with several fungal taxa.
Ecological flexibility: These partnerships allow orchids to thrive in nutrient-poor environments — including tropical canopies, temperate forests, and even alpine habitats.
Evolutionary persistence: Many orchids retain their dependence on fungi even in adulthood, while others become photosynthetic after initial germination.

Interestingly, these symbiotic relationships are not always mutualistic in the classic sense. In many cases, the orchid benefits while the fungus receives little or nothing in return — a subtle form of biological exploitation that has persisted through deep evolutionary time.

The orchid–fungus relationship is therefore an excellent example of coevolution and evolutionary opportunism, illustrating how plants adapt to ecological constraints through symbiosis rather than through “perfect design”.

The research is explained in a Kobe University press release:

Deadwood brings wild orchids to life
Deadwood-decomposing fungi feed germinating orchids, providing the carbon their tiny seeds don’t have. The Kobe University finding not only closes a gap in our understanding of wild orchid ecology but also uncovers an important carbon flux in the ecosystem.

Close-up of Cremastra variabilis seedlings (white) entwined with fungal hyphae near decaying wood, illustrating how wood-decomposing fungi sustain seedling growth.

© INUI Kazuki (CC BY)

Orchid seeds are as small as dust and do not provide any nutrients for the young plant to grow. The adult plants are known to rely on a certain type of fungi that develop structures within the plant’s roots, but whether these same fungi also help with germination has not been established.

Studying orchid germination in nature is notoriously difficult. In particular, the painstaking methods required for recovering their seedlings from soil explain why most earlier studies focused only on adult roots, where fungi are easier to sample.

Kenji Suetsugu, lead author.
Department of Biology
Graduate School of Science
Kobe University, Kobe, Hyogo, Japan.

During fieldwork, Suetsugu’s team noticed a strange pattern. He says:
We repeatedly found seedlings and adults with juvenile root structures near decaying logs, not scattered randomly in the forest. That recurring pattern inspired us to test whether deadwood fungi fuel orchid beginnings.

Kenji Suetsugu.

These juvenile root structures are coral-shaped rhizomes and have been interpreted as a seedling’s organ retained into adulthood — and they are often associated with wood-decaying fungi rather than with those found in adult orchids without these structures. Being experts in orchid ecology and evolution, Suetsugu’s team took on the challenge to find out who feeds the young orchids. In the journal Functional Ecology, the Kobe University team report that amongst seeds of four model orchid species they buried in various forest locations, they observed germination only near decaying logs, and that the seedlings virtually exclusively associated with wood-decaying fungi.

We were struck by how exclusive and consistent these fungal partnerships were. There is an almost perfect match in the fungi that seedlings of a given orchid species associate with and the fungi on adult plants with coral-shaped rhizomes of the same species. We think that the plants without coral-shaped rhizomes shift to other fungi as their nutritional needs change during growth and the carbon source offered by rotting logs dries out.

Kenji Suetsugu.

Among the relatives of the orchids the Kobe University team studied, there are many species that have independently evolved full mycoheterotrophy, that is, they have abandoned photosynthesis and instead feed on fungi throughout their lives.
The propensity of these orchids to maintain their association with wood-decaying fungi into adult life probably facilitated their evolution of full mycoheterotrophy.

Kenji Suetsugu.

In the paper, the team writes, “As woody debris represents a major carbon source in forests, associations with wood-decaying fungi may enhance carbon acquisition, especially in warm, humid habitats.”
For conservation, our results mean that protecting orchids in the wild is inseparable from protecting deadwood and its fungi. For ecological sciences, they reveal a hidden carbon route from deadwood to green plants, explaining how seedlings can establish themselves on dark forest floors. And they show that deadwood is not dead — it is a cradle of new life.

Kenji Suetsugu.

Publication:
Suetsugu, K., & Okada, H. (2025).
The nexus of decay and birth: Ecological and evolutionary significance of wood-decaying fungi in green Calypsoinae orchid germination. Functional Ecology, 00, 1–13. https://doi.org/10.1111/1365-2435.70181

The nexus of decay and birth: Ecological and evolutionary significance of wood-decaying fungi in green Calypsoinae orchid germination
Kenji Suetsugu & Hidehito Okada
First published: 30 September 2025 https://doi.org/10.1111/1365-2435.70181

Abstract

A key feature of Orchidaceae is the production of dust-like seeds that depend on fungal carbon during early development. Although protocorms and mature green orchids typically associate with rhizoctonia fungi, many non-photosynthetic orchids and some photosynthetic green orchids maintain symbioses with saprotrophic (SAP), non-rhizoctonia fungi throughout their lives.
We examined the mycorrhizal communities of four green Calypsoinae orchids (Calypso bulbosa, Cremastra variabilis, Oreorchis patens and Tipularia japonica) at germination. Using seed baiting combined with molecular barcoding, we tested for potential associations with SAP, non-rhizoctonia fungi at the protocorm stage, given that conspecific adults with coralloid rhizomes, structures morphologically resembling protocorms, often associate with these fungi. We also measured natural abundances of 13C and 15N in T. japonica protocorms, coralloid rhizome-bearing adults, individuals lacking coralloid rhizomes and autotrophic reference plants to quantify the contribution of fungal carbon to plant nutrition.
Germination was observed exclusively near adult plants with coralloid rhizomes and decomposing wood, whereas seeds placed near adults lacking coralloid rhizomes failed to germinate. Molecular barcoding revealed that protocorms of all four species were predominantly associated with wood-decaying fungi. Their mycorrhizal communities closely matched those of conspecific adults with coralloid rhizomes, and the dominant operational taxonomic unit (OTU) was even shared across protocorms and coralloid rhizomes of C. variabilis and O. patens. Stable isotope analyses further indicated that T. japonica protocorms derived all their carbon from wood-decaying fungi, while coralloid rhizome-bearing adults obtained more than half of their carbon from these fungi.
These results underscore the role of SAP, non-rhizoctonia fungi in germination and suggest that wood-derived carbon facilitates seedling establishment in shaded forests. This broadens our understanding of plant adaptation to low-light environments and deepens our knowledge of the functional diversity of mycorrhizal interactions. Moreover, because many fully mycoheterotrophic Calypsoinae species possess coralloid rhizomes exclusively colonized by SAP non-rhizoctonia fungi, such germination-stage associations in green Calypsoinae may have promoted the repeated evolution of full mycoheterotrophy in this group.

1 INTRODUCTION
The family Orchidaceae is one of the most species-rich angiosperm families, exhibiting remarkable diversity across a wide range of habitats worldwide. A defining characteristic of orchids is their production of numerous dust-like seeds (Arditti & Ghani, 2000). In natural environments, orchid seeds rely on mycorrhizal fungi for essential nutrients such as carbon, nitrogen and phosphorus during early development, resulting in fully mycoheterotrophic underground seedlings (protocorms) (Jacquemyn & Merckx, 2019; Merckx, 2013; Rasmussen & Rasmussen, 2014).

At maturity, many orchids shift toward partial autotrophy, and some eventually achieve full autotrophy, even supplying carbon to their fungal partners (Cameron et al., 2008). However, some orchids continue to depend partially or entirely on mycorrhizal fungi for carbon in adulthood (Gebauer & Meyer, 2003; Hynson et al., 2013.1). Fully mycoheterotrophic plants, which are non-photosynthetic and completely reliant on fungi, are especially prevalent in Orchidaceae, including over 200 species and more than 30 independent evolutionary origins (Merckx & Freudenstein, 2010). This early dependence on fungal carbon may have facilitated multiple transitions to fully mycoheterotrophy in orchids (Hynson et al., 2013.1; Jacquemyn & Merckx, 2019; Merckx, 2013).

Due to their subterranean nature, empirical data on fungal associations at the seedling stage remain limited. However, seed baiting techniques (e.g. sowing seeds in mesh bags) combined with molecular barcoding have greatly advanced our understanding of mycoheterotrophic germination (Rasmussen & Whigham, 1993). The fungal partners of orchid seedlings generally correspond to those found in co-occurring adult plants (Jacquemyn et al., 2012; McKendrick et al., 2002; Rasmussen & Rasmussen, 2014). Orchid seedlings that transition to autotrophy or a low degree of mycoheterotrophy in adulthood typically associate with polyphyletic rhizoctonia fungi (Tulasnellaceae, Ceratobasidiaceae and Serendipitaceae), which also colonize adult roots (Dearnaley et al., 2012.1; Rasmussen & Rasmussen, 2014). In contrast, both seedlings and adults of fully mycoheterotrophic orchids, as well as partially mycoheterotrophic orchids with high fungal carbon dependence, are predominantly associated with ectomycorrhizal (ECM) fungi or, less commonly documented, with saprotrophic non-rhizoctonia (SAP) fungi (Bidartondo & Read, 2008.1; Jacquemyn & Merckx, 2019).

At finer taxonomic scales, many orchids exhibit developmental shifts in fungal partners, although the fungal communities often overlap at the genus or family level across life stages (Bidartondo & Read, 2008.1; Meng et al., 2019.1; Ventre Lespiaucq et al., 2021). For example, a specific Tulasnella species consistently isolated from mature Dendrobium moniliforme promotes protocorm formation but not further development, whereas a different Tulasnella species supports seedling establishment (Meng et al., 2019.1). Similarly, in Cephalanthera longifolia, early developmental stages involve a subset of the fungal taxa found in germinating seeds and adult roots (Bidartondo & Read, 2008.1).

More pronounced symbiont shifts are often observed in orchids that associate at least partially with SAP fungi. For example, the fully mycoheterotrophic Gastrodia elata initially depends on litter-decomposing Mycena species for germination but later associates with wood-decomposing Armillaria species (Park & Lee, 2013.2). Similarly, protocorms of Tipularia discolor associate with specific Auriculariales fungi, while the photosynthetic adults form relationships with rhizoctonia fungi (McCormick et al., 2004). Likewise, Oeceoclades maculata germinates with a single Psathyrella species but later broadens its associations to include rhizoctonia fungi such as Ceratobasidiaceae and Tulasnellaceae (Bayman et al., 2016). Additionally, Psathyrellaceae fungi dominate in protocorms and seedlings of Cremastra appendiculata, while rhizoctonia fungi predominate in the roots of mature plants (Zahn et al., 2022). Nonetheless, SAP associations at the germination stage in green orchids are still considered exceptional (Bayman et al., 2016).

Interestingly, some green orchids such as Cremastra variabilis, a sister species of C. appendiculata, occasionally possess coralloid rhizomes in adulthood, structures commonly observed in fully mycoheterotrophic species (Maekawa, 1971). These rhizomes resemble conspecific protocorms morphologically and are often interpreted as persistent protocorms retaining juvenile features (Freudenstein, 1994; Gillman, 1876; MacDougal, 1899; Maekawa, 1971). Recent studies have linked coralloid rhizomes with both the degree of mycoheterotrophy and associations with SAP fungi (Suetsugu et al., 2022.1; Suetsugu & Matsubayashi, 2021.1; Yagame et al., 2021.2). We therefore hypothesize that protocorms in species whose adults occasionally produce coralloid rhizomes and associate with SAP fungi are colonized by the same fungal taxa found in conspecific coralloid rhizomes. Given that orchids fully depend on fungal-derived carbon during the protocorm stage (Merckx, 2013) and that wood-decaying fungi are likely better carbon sources than rhizoctonia fungi (Suetsugu & Okada, 2025b), these interactions are also ecologically plausible.

Here, we focused on four green orchid species in the subtribe Calypsoinae: Calypso bulbosa, C. variabilis, Oreorchis patens and Tipularia japonica. A recent phylogenomic analysis revealed that the monotypic genus Calypso forms a clade with Changnienia and Tipularia (approximately five species), while Cremastra (approximately seven species) is grouped with Aplectrum, Oreorchis (approximately 17 species), Kitigorchis (approximately two species) and Corallorhiza (approximately 13 species) (Barrett et al., 2025.1). These Calypsoinae taxa have emerged as a model system for studying mycorrhizal associations and mycoheterotrophy due to their diverse fungal partners and nutritional strategies (Barrett et al., 2010.1; Barrett & Freudenstein, 2011; Freudenstein & Barrett, 2014.1; Suetsugu & Matsubayashi, 2021.1; Suetsugu & Okada, 2025.2a, 2025b). Among the species examined, three are known to occasionally develop coralloid rhizomes at maturity that are associated with SAP fungi: C. bulbosa with Auriculariales fungi, and C. variabilis and O. patens with Psathyrellaceae fungi (Suetsugu et al., 2022.1; Suetsugu & Matsubayashi, 2021.1; Suetsugu & Okada, 2025b; Yagame et al., 2021.2). In these species, the occurrence of coralloid rhizomes together with SAP associations is linked to increased levels of mycoheterotrophy (Suetsugu et al., 2022.1; Suetsugu & Matsubayashi, 2021.1; Suetsugu & Okada, 2025b; Yagame et al., 2021.2). Tipularia japonica may exhibit similar traits, as seed germination in the close relative T. discolor is stimulated by decaying wood and the protocorms of T. discolor associate with wood-decomposing Auriculariales fungi (McCormick et al., 2004, 2012.2; Rasmussen & Whigham, 1998; Whigham et al., 2002.1).

Consequently, we characterized the mycorrhizal communities of these four species at the protocorm stage to improve our understanding of SAP-associated mycoheterotrophic germination. Specifically, we addressed the following questions: (i) Are the mycorrhizal communities at the protocorm stage dominated by SAP fungi, and if so, do they resemble those found in the coralloid rhizomes of conspecific adults? (ii) Is mycorrhizal community composition during the initial mycoheterotrophic stage similar across species, particularly between C. variabilis and O. patens, which are potentially associated with Psathyrellaceae fungi, and between C. bulbosa and T. japonica, which may be associated with Auriculariales fungi? (iii) Does germination occur more frequently near adult plants bearing coralloid rhizomes than near those lacking such structures? (iv) As in the other three species, do T. japonica individuals with coralloid rhizomes exhibit a high degree of mycoheterotrophy?

Suetsugu, K., & Okada, H. (2025).
The nexus of decay and birth: Ecological and evolutionary significance of wood-decaying fungi in green Calypsoinae orchid germination. Functional Ecology, 00, 1–13. https://doi.org/10.1111/1365-2435.70181

Copyright: © 2025 The authors / British Ecological Society.
Published by John Wiley & Sons, Inc. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

In short, the orchid–fungus relationship is an exquisite example of evolutionary opportunism rather than intelligent planning. An intelligent designer would surely have equipped the orchid with the ability to germinate and grow independently, without relying on an external fungal partner to supply essential nutrients. Instead, what we observe is a clumsy, roundabout system in which a plant cannot even begin its life without hijacking another organism’s resources.

This arrangement is riddled with potential failure points: the seed must land in precisely the right place, encounter the right fungus, and form a successful association before it can germinate. Any step that fails means the seed simply dies. Such a fragile, contingent mechanism is the opposite of elegant design — it is exactly what we would expect from an undirected, evolutionary process that builds opportunistically on existing biological relationships rather than starting from an ideal blueprint.

Creationists often point to complexity as though it were evidence of design. In reality, the orchid–fungus relationship illustrates how evolutionary processes generate unnecessary and inefficient complexity over time. The system works, but it does so in the most roundabout and failure-prone way imaginable — a hallmark not of foresight and intelligence, but of blind, tinkering evolution.

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