Tagged: moss


Marimo balls

Algal research that has its ups and downs…

Every so often you chance upon a scientific study that makes you think “What? That’s new or worthy of study (and publication…)?” I had that reaction when I saw the paper entitled, “Photosynthesis and circadian rhythms regulate the buoyancy of marimo lake balls” by Dora Cano-Ramirez et al.. Marimo balls are spheres of Aegagropila linnaei [a filamentous, multicellular, freshwater green alga]. The ‘phycospheres’ are found in shallow freshwaters such as lakes in Iceland, and – most famously – in Lake Akan in Japan. Although Lake Akan is home to an estimated population of 600 million marimo – some exceeding 30...

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Preserved mosses discovered in Upper Jurassic rocks of Argentinean Patagonia

Exquisitely preserved tiny fossils are key for understanding moss evolution

Tiny 135-million-year-old moss fossils found in rocks from western Canada preserve exquisite anatomical details. These fossils open an unexpected window on moss evolution, as they allow for recognition of living moss lineages deep in the fossil record. This way, they add to the notoriously sparse fossil record of the group. Click images to enlarge Cretaceous rocks on Vancouver Island (British Columbia) (FIG 1) are revealing rich assemblages of plant fossils (FIG 2) that contain a broad diversity of minute mosses. The moss fossils show unexpectedly delicate anatomical detail at very small scales. Some reveal the arrangement of diverse cell types...

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A leaf viewed through a microscope

Amazing moss and how to identify it

If I told you that during a 200m walk down a suburban London street I saw 13 different species from one group of organisms, you might struggle to imagine what I could have seen. You’d probably be even more surprised to learn that this significant diversity belongs to one of our most unassuming plant groups: the mosses. Even as an unashamed plant enthusiast and keen botanist, I’ve always struggled to get my head around mosses. How can it be possible to tell apart such tiny and uniform plants? Or so I thought. A fantastic week on the Natural History Museum’s...

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Spore liberation in mosses

The ability to perform hygroscopic movements has evolved in many plant lineages and relates to a multitude of different functions such as seed burial, flower protection or regulation of diaspore release. In a recent Editor’s Choice article published in AoB PLANTS, Gallenmüller et al. provide an analysis of spore liberation in mosses in response to humidity conditions. The study presents, for the first time, temporally and spatially well-resolved kinematic analyses of the complex hygroscopic movements performed by the peristome teeth inserted at the mouth of the spore capsule and gives insights into their sophisticated functional morphology and anatomy. The authors...

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Ceratodon purpureus

Sex-specific morphology and physiology in Ceratodon purpureus

Separate sexes and biased sex ratios are common in bryophytes, yet little is known about how fine-scale, sex-specific morphological traits are correlated with physiology and population sex-ratios. Slate et al. analysed cellular, leaf, and canopy traits and photochemical measurements in the dioecious moss Ceratodon purpureus. Male and female plants differed in cell, leaf and photochemical measures. These sexual dimorphisms were female biased, with females having larger and thicker leaves and greater values for chlorophyll fluorescence-based, leaf photochemistry measurements than males. Female traits were also more variable than male traits. Interestingly, field population sex ratios were significantly male biased in two...

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Scanning electron microscope photographs of the investigated moss spores.

Spore settling velocity to assess moss dispersal rates

The settling velocity of diaspores is a key parameter influencing dispersal ability in wind-dispersed plants but remains largely undocumented in bryophytes. Zanatta et al. measured this parameter for nine species using a fall tower design combined with a high-speed camera and determine that, while settling velocity can be estimated by spore diameter in most of the cases, some spores show important departures from theoretical expectations. The authors investigate the potential causes of this divergence by taking specific variation in spore shape and surface roughness into account and suggest that this affects the balance between density and drag.

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Aloina ambigua

Embryonic moss sporophytes can be hardened to desiccation tolerance

Embryos of the moss Aloina ambigua are inducibly desiccation tolerant (DT), requiring a slow-dry period to confer tolerance to air-dryness. Hardening to DT describes a condition of temporary tolerance to a rapid-dry event (<30 min from full turgor to air-dryness) that is conferred by a prior slow-dry event. Brinda et al. found for the first time that moss embryos can indeed be hardened to DT, by first slowly drying embryos and equilibrating them at 50 % relative humidity, then rehydrating the embryos and exposing them to a rapid dry event at intervals of 24 h. The degree of hardening to...

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Moss sporophytes

The March 2013 issue of Annals of Botany is now Free Access

The March 2013 issue of Annals of Botany is now Free Access. The cover image is of two generations of moss, the younger sporophytes growing from the parent gametophyte. AJ Cann blogged about this paper last year. If you get confused between sporophytes and gametophytes, then you’re not alone. Plants alternate generations between sporophytes and gametophytes. The children of oak trees aren’t acorns, they’re grandchildren. The ‘children’ of oaks would be pollen and the embryo sacs they pollinate. Contrary to popular belief pollen isn’t plant sperm.

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