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Orthotrichum-tanganyikae-Pde-la-Varde-QHWang-YJia-comb-nov-A-B-plants-C.png from: https://www.researchgate.net/figure/Orthotrichum-tanganyikae-Pde-la-Varde-QHWang-YJia-comb-nov-A-B-plants-C_fig1_306034210

Mielichhoferia speluncae: The Fascinating Cave-Dwelling Moss

Introduction

When you think of mosses, you might picture them growing on trees, rocks, or forest floors. But did you know there’s a unique species of moss that makes its home in the depths of caves? Meet

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X-2009112409023273493.jpg from: https://www.canada.ca/fr/environnement-changement-climatique/services/registre-public-especes-peril/evaluations-rapports-situations-cosepac/bryum-porsild/chapitre-3.html

Mielichhoferia speluncae P.de la Varde, a tiny but remarkable moss in the Mniaceae family. In this post, we’ll dive into the fascinating world of this cave-dwelling bryophyte.

Orthotrichum-tanganyikae-Pde-la-Varde-QHWang-YJia-comb-nov-A-a-portion-of_Q640.jpg

Orthotrichum-tanganyikae-Pde-la-Varde-QHWang-YJia-comb-nov-A-a-portion-of_Q640.jpg from: https://www.researchgate.net/figure/Orthotrichum-tanganyikae-Pde-la-Varde-QHWang-YJia-comb-nov-A-a-portion-of_fig2_306034210

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Moss_19_WHG19A.jpg from: https://wshg.net/the-garden/2019-02-14/bloedel-reserve-moss-gardens/

Background on Mielichhoferia Mosses

The genus Mielichhoferia contains around 40 species of mosses found across the globe. They are small acrocarpous mosses, meaning they produce sporophytes at the tips of their stems. Mielichhoferia mosses often grow on rocks or in crevices.
What makes M. speluncae stand out is its preference for growing in caves and caverns, an unusual habitat for most mosses. It was first described by French botanist Pierre de la Varde in 1927 from specimens collected in caves in France.

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be953b5de6d86f9f25213373f32a37361acc1ec8 from: https://identify.plantnet.org/useful/species/Microlepia speluncae (L.) T. Moore/data

Morphology and Identification

M. speluncae forms small, dense cushions or turfs on rock surfaces. The individual plants are tiny, only 2-10 mm tall. Leaves are lanceolate (lance-shaped) and have a strong midrib that extends to the leaf tip. Leaf margins are entire (smooth-edged).
The sporophytes are key for identification. Capsules are pyriform (pear-shaped) and inclined to pendulous on a long seta (stalk). Peristome teeth are well-developed. Spores mature in summer.

Global Distribution and Habitat

M. speluncae has a scattered distribution across Europe, Asia, and North America. It is found in limestone caves and grottos, often in twilight zones with some natural light and higher humidity.

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Dicranum-scoparium.jpg from: https://biologydictionary.net/moss/


The moss grows directly on rock (epilithic) or on thin soil over rock. It tolerates low light conditions and is often the only plant able to grow in the deeper recesses of caves.

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ef5ad7e0ee7485b37c149e1aadb6a5d6.jpg from: https://www.pinterest.com/pin/368169338259426921/

Ecological Roles and Adaptations

As one of the few plants in caves, M. speluncae plays an important role in these ecosystems:

To thrive in the harsh cave environment, M. speluncae has several adaptations:

  • Tolerance of low light levels for photosynthesis
  • Ability to absorb water and nutrients directly through leaves
  • Asexual reproduction via gemmae to colonize surrounding areas
  • Possible bioluminescence to attract insects for spore dispersal (still being researched)

Conclusion

The unassuming

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nowellia.jpg from: https://saratogawoodswaters.blogspot.com/2011/11/mosses-and-more-on-mountain.html

Mielichhoferia speluncae moss is a true cave-dweller, carving out a niche in one of Earth’s darkest, most inhospitable environments. Its ability to survive where few other plants can is a testament to the incredible adaptability of mosses.
Next time you explore a cave, keep an eye out for this tiny but tenacious bryophyte! And consider this: what other secrets might still be hidden in the depths of caves, just waiting to be discovered?