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Dudresnaya verticillata (Withering) Le Jolis
Le Jolis
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RHODOPHYCEAE
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(Dudresnaya's whorled weed)
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| Photo details | ||
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Small plant growing on maerl. Scale: Plant length 7 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By:C. Maggs |
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| Identification Notes | ||
| A very lubricious and fragile species which forms a much branched bushy growth up to 200 mm long with the terete branches up to 2 mm in diameter and with a banded appearance when young. The branching is irregularly alternate and plants are attached by a small discoid holdfast. Texture is soft, delicate and fragile and the colour ranges from rose-pink to dark red. Other characterising features: Within the jelly-like structure is an axial filament which bears radiating whorls of 4 delicate and repeatedly dichotomous ' radial filaments' composed of club-shaped cells about 10 µm in diameter and 25 µm long. These filaments can only be seen in the youngest parts of the plant, giving them a banded appearance. As the plants ages the radial filaments produce branched intertwined rhizoids which obscure the internal structures. Plants are monecious with colourless spermatangia borne terminally. cystocarps are scattered throughout the plant and are very small, up to 125 µm in diameter. Tetrasporangia are borne laterally on the radial filaments and are 25 to 53 x 11 to 23 µm with zonately arranged spores. Grows in early spring, not becoming conspicuous until summer when plants become fertile and then disappear in October. Irvine, 1983 |
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| Confusion | ||
| Schmitzia spp. and Calosiphonia vermicularis are similar mucilaginous algae but the radiating filaments are embedded in a jelly that keeps the ends together, whereas in Dudresnaya the tips of these filaments are loose, giving a shaggy appearance under the dissecting microscope. In C. vermicularis, the radial filaments are patent, short and much branched with a branch usually arising from each axial cell. In D. verticillata, the radial filaments are long with branches occurring at intervals of between 3 and 7 cells. |
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| Habitat | ||
| Epilithic and occasionally epiphytic sublittorally to 13 m, often on pebbles, maerl and in areas with tidal current. |
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| Recorded distribution | ||
| Sporadically recorded on southern and western shores of the British Isles from the south coast of England to Shetland. |
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| Researched by | ||
| F. Bunker / C. Maggs |
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| Synonyms | ||
| Acknowledgements | ||
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Additional Photos
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| Small plant growing on maerl. Scale: Plant length 7 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Whole plant in tray. Scale: Plant width 15 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By: | ||
| Close up of branch in tray. Scale: Width of branch shown approximately 7 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By: | ||
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