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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

Plants bearing multiple sporophytes fail to support all offspring efficiently. Sporophytes on polysetous shoots take longer to mature and are smaller than those of monosetous shoots. It is better for the majority of mosses to put all their energy into a single sporophyte. 12/

Data showing that spore capsules from polysetous shoot apices are on average smaller in diameter than those from monosetous apices. This means that they produce significantly fewer spores in addition to having longer maturation times. A disadvantage for mosses.

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

When we knocked out -C using CRISPR, all lines grew like WT and had similar shapes and numbers of gametangia. However, all 4 -c mutants had an increase in polysety - twin and triplet sporophytes originating from different fertilised eggs on the same plant apices! 10/

A wild-type shoot with a single apical sporophyte (left) beside a Ppwox13lc mutant with three sporophytes on the same shoot (right).

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

However, when plants with very early embryos were examined after fertilisation, the embryos lacked expression while surrounding inactive eggs/zygotes stained strongly. Expression was therefore absent from the one egg of several that eventually becomes the single embryo/sporophyte of the moss... 9/

A shoot apex of a PpWOX13LC promoter-reporter line containing several archegonia with eggs/zygotes following fertilisation, and a central archegonium containing a very young embryo. As this is WT, only one embryo/sporophyte normally forms per apex. The embryo lacks -C promoter activity while the adjacent archegonia with inactive eggs/zygotes strongly stain. This suggests that -C may have a role in sporophyte activation similar to its full-length counterparts, PpWOX13LA/-B.

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

Next, we further validated this by generating and examining promoter-reporter lines. Here, we visualised promoter activity in reproductive organs, particularly in eggs... 8/

Archegonia (egg-producing) and antheridia (spermatozoid-producing) gametangia have C promoter activity in the gametes during development. In archegonia, activity is switched off when the egg is mature.

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

We investigated predicted 3D protein structures of the two classes of genes and found that the DNA-binding homeodomains (HDs) of the -C genes were conserved and intact. All -C genes lacked 3-prime motifs but gained a small, postitive charged extension to the HD. This again suggested function... 6/

Motifs and 3D protein structures of PpWOX13LA and -C

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

We sampled 19 moss genomes and were surprised to find that PpWOX13LC belonged to a larger clade of similar truncated moss WOX genes present in all sampled genomes except for Sphagnum and Takakia. These genes are present in 99% of extant mosses, indicating that they may indeed be functional! 5/

Cladogram showing that WOX13LC proteins arose long ago in moss evolution and were retained in most mosses. Interestingly, Sphagnum mosses have independently evolved truncated WOX genes in two clades - they are not C-like and we have no idea what they do.

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/06/2026

Happy to announce our study that has just been published from work done during my PhD at the University of Bristol working in Prof. Jill Harrison's lab. It's about WOX genes and sporophyte development in the model moss, Physcomitrium patens. Take a look 🧵👇

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George R. L. Greiff @ilichenmoss2.bsky.social · 07/04/2026

Habitat of vertical rock faces near waterfall. The fungus wasn't possible to see in the field - I only noticed some of the other, larger fungi on the plant.

A figure panel showing a small waterfall on the left and two macro shots of infected Diplophyllum albicans on the right. No fungi are visible in the latter.

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George R. L. Greiff @ilichenmoss2.bsky.social · 06/04/2026

Nice to find good material of a tiny fungus, Bryobroma caudatum, on the liverwort Diplophyllum albicans yesterday. The fungus produces tiny fruitbodies up to only 75 microns diam. and spores with little tails. The distinctive mycelium forms a network over the host cell walls without killing them.

Two shoots of the liverwort, Diplophyllum albicans, under the compound microscope at around x100 total magnification. They have dark reddish-brown stems and green leaves. There are small, black spots on some of the leaves along with tiny open networks of brown, anastomosing hyphae.

A ruptured black-brown fruitbody of Bryobroma caudatum with two hyaline, globose immature asci emerging from it. The fruitbody is sitting on a fragment of leaf tissue with mycelium on top of it. Image at x1000 magnification.

Some ellipsoidal, hyaline ascospores beside a ruptured fruitbody of the fungus. One with a tail is indicated by an arrow.

The mycelium of B. caudatum and related species is formed of conspicuous brown hyphae that mostly grow on top of the anticlines of the host cells, occasionally forming tiny pin haustoria that penetrate the cell walls (not easily visible unless sections are made). The host cells cytoplasm is intact and the underlying cells are living, with chloroplasts and oil bodies. Image at x1000 magnification.

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George R. L. Greiff @ilichenmoss2.bsky.social · 23/09/2025

A final micrograph for today showing mycelium of an Epibryon sp. fungus inside liverwort cells. Most cells are infected but some in the lower part of the photo are healthy, as evidenced by the absence of hyphae and the presence of oil bodies.

Micrograph of liverwort cells, some of which are infected with brown fungal hyphae while others are healthy and contain plastids and oil bodies.

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George R. L. Greiff @ilichenmoss2.bsky.social · 23/09/2025

Micrograph of a rhizoid gall caused by a chytrid on Bryum moss. The infected cell contains several zoosporangia, some of which have thread-like exit tubes that release flagellated spores. Chytrids are interesting fungi that mostly lack hyphae and have mobile spores.

A rhizoidal gall on Bryum sp. from mud in a reservoir draw-down zone. It is club-shaped and curved, containing five chytrid zoosporangia inside it, which are spherical. Some of the zoosporangia have thread-like exit tubes leading to the outside, which liberate zoospores that infect other cells.

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George R. L. Greiff @ilichenmoss2.bsky.social · 23/09/2025

B. scapaniae is closely related to B. gymnomitrii on Gymnomitrium species. Both fungi grow on the lower parts of host shoots. The larger ascomata of the latter make it slightly easier to spot. Both fungi are very rarely recorded.

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George R. L. Greiff @ilichenmoss2.bsky.social · 23/09/2025

Great to find the fungus Bryobroma scapaniae on Scapania undulata in Bannau Brycheiniog in Wales a few days ago. I think this is the third ever record of the species, and I see how it is very easy to miss, with the dark fruitbodies disguised against the black host stem. From a rock in a stream.

A single shoot of Scapania undulata photographed against a white background. The apex is green while the brown lower parts display infection (arrowed). Bryobroma scapaniae presents as clustered black ascomata and infected tissues are covered by a dense, dark brown mycelium network.

Zoomed in on some infected leaves with dark brown, branching mycelium and black fruitbodies.

Clusters of black fruitbodies on largely leafless basal part of the plant shoot.

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George R. L. Greiff @ilichenmoss2.bsky.social · 13/08/2025

Using one of my favourite bryophyte books to help with my thesis. It is a difficult read, densely packed with all kinds of interesting and almost forgotten information. I must have read it half a dozen times, and each time, I notice something profound that I either missed or didn't understand before

The book, "The Structure and Life of Bryophytes" by E. V. Watson. It has a green and white cover with line drawings of bryophytes on it.

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George R. L. Greiff @ilichenmoss2.bsky.social · 12/07/2025

It was nice to go for a run past the spot that got me interested in bryophytes 10 years ago when I was staying at my grandfather's place. I was struck by the outerwordly appearance of the liverwort Conocephalum conicum, which was completely covering the wall of this bridge back then.

Strava map of run route along cycle track with mossy bridge indicated by arrow.

North-facing wall of Victorian railway bridge with seepage supporting bryophytes, particularly Conocephalum conicum.

The liverwort Conocephalum conicum growing on damp brickwork, the bryophyte that started it all for me 10 years ago.

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George R. L. Greiff @ilichenmoss2.bsky.social · 12/04/2025

The fungi that grow on bryophyte (moss) sporophytes are usually completely different to those on gametophytes. One feature is less apparent specificity in many, where generalists can grow on decaying vascular plants and "woody" moss sporophytes. This is a spore of Pleospora cf. herbarum ... 1/2

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George R. L. Greiff @ilichenmoss2.bsky.social · 22/03/2025

A hornwort, Phaeoceros laevis, I think, on a seepage. Lovely to see the plant is still abundant at the site.

A mat-like, dark green plant with lighter, horn-like structures projecting from it.

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George R. L. Greiff @ilichenmoss2.bsky.social · 23/02/2025

Interesting collection. It does remind of Vezdaea in the first instance but the presence of filamentous paraphyses makes it less certain to me. The black colour is also unexpected. The asci are immature in the zoomed photo. Spores seem ellipsoid. To me, the best Vezdaea to fit is V. stipitata.

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George R. L. Greiff @ilichenmoss2.bsky.social · 05/02/2025

Nice to find a patch of the bryophilous fungus Luteodiscus epibryus on Lepidozia reptans last weekend. It is a lovely species to keep an eye out for on bryophyte-covered rotting wood, especially on liverworts like Nowellia. It has an unusually wide host range, including mosses and liverworts.

A tiny, brown-stalked, orange cup fungus on the tip of a leafy liverwort plant.

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George R. L. Greiff @ilichenmoss2.bsky.social · 19/01/2025

Bryoscyphus dicrani on Ceratodon purpureus. It is probably not very rare, but this was the first time I saw it. Found on Christmas Day last year. Neat little thing.

Light brown-orange cup fungus on straw-coloured moss shoot.

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George R. L. Greiff @ilichenmoss2.bsky.social · 18/01/2025

Great to see a bryophilous fungus, Bryonectria cuneifera, which lives between the lamellae of leaves of the moss Polytrichum formosum. This species has evaded me for nearly 8 years so glad to finally find it.

Two fruitbodies of B. cuneifera emerging from the space between the leaf lamellae.

Fungal mycelium stained in lactophenol cotton blue showing the round appressoria.

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George R. L. Greiff @ilichenmoss2.bsky.social · 31/12/2024

Two moss patches with bleached areas that harbour fungal fruitbodies. Not all such patches have fungi but they are a good indication that something is not quite right with the moss.

A patch of bright green moss with a central brown part.

A bleached clump of moss among green moss.

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George R. L. Greiff @ilichenmoss2.bsky.social · 25/12/2024

Mniaecia jungermanniae and Lophocolea semiteres male plants spotted on my Christmas Day walk.

Green liverwort shoot with male reproductive organs below the apices.

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George R. L. Greiff @ilichenmoss2.bsky.social · 14/12/2024

Fantastic to find the bryophilous fungus Octospora mnii today, a new record for the British Isles. I found an ambiguous specimen a few years ago, but this one is unmistakable. It is parasitic on the persistent protonema of the moss Rhizomnium punctatum.

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George R. L. Greiff @ilichenmoss2.bsky.social · 14/12/2024

Nice to see the very tiny fungus Bryonectria callicarpa today on Frullania dilatata, a species that is practically impossible to see in the field. It forms tiny orange perithecia on the undersides of host plants and causes no obvious symptoms.

Orange perithecium sitting under leaf of liverwort shown from below, with neck oriented towards the dorsal side of the plant.

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George R. L. Greiff @ilichenmoss2.bsky.social · 22/11/2024

A nice sample of the rarely recorded bryophilous fungus Epibryon diaphanum (black spots) on the common moss Hypnum cupressiforme.

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George R. L. Greiff @ilichenmoss2.bsky.social · 30/08/2024

Not fun to see my least favourite plant, ivy, overgrowing a mossy wall. Ivy is an increasing but largely unacknowledged problem, with the capacity to rapidly overgrown and outcompete diverse communities of bryophytes and lichens - on rocks, trees and the ground...

New growth of ivy covering mosses on a wall. At least 6 moss species here are threatened with being out-competed.

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George R. L. Greiff @ilichenmoss2.bsky.social · 21/08/2024

Planted up some Marchantia polymorpha fragments from a population outside of my flat for an outreach project. Let's see if they grow!

Small apical fragments of green Marchantia polymorpha plants growing on soil in a plastic punnet container.

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George R. L. Greiff @ilichenmoss2.bsky.social · 13/08/2024

Finally, I bit the bullet and moved over from the other place. Posting a celebratory piece of moss parasitised by the fungus Bryorella acrogena! Hoping to (re-)connect with former plant science twitter.

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