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Rhodothamniella floridula (Dillwyn) J Feldmann
Le Jolis
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RHODOPHYCEAE
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(red rose-grass weed)
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| Photo details | ||
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Close up of plants showing sand binding habit. Scale: Plant length approximately 2 cm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs |
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| Identification Notes | ||
| This is a small filamentous species which characteristically occurs as a dense and spongy sand-binding turf that can cover large areas of the mid and lower shore. Plants have both erect and prostrate axes consisting of chains of cells 60 to 120 µm in length and 20 to 30 µm in diameter when mature. Erect axes grow up to 3 cm in height and are sparsely branched in an irregular and variable manner, with branching frequency increasing towards the apices. Specialised lateral filaments are produced which interweave with the erect axes to produce a complex network to which sand particles adhere with the result that R. floridula forms a dense sandy turf. Plants without binding sand are filamentous, soft and flaccid. The colour of erect axes is a brownish red (unless bleached by the sun) and the basal parts which are normally buried in sand are either colourless or greenish. Other characterising features: Gametangial plants have not been found in the field in Europe. Tetrasporangia are found mainly in winter (November to March) and are ovoid, 20 to 40 µm in diameter, and occur either singly or in clusters of between 2 to 5 towards the end of the erect axes, with or without a 1 to 3 celled stalk. floridula turfs are at their most luxuriant in the winter whereas in summer they become bleached and may die back, losing sand. |
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| Confusion | ||
| No other filamentous red species has the sand binding properties of R. floridula and so the identity of this species is unlikely to be confused when growing in sand. Rhodochorton purpureum similarly forms extensive turfs but these are mostly on higher-shore bedrock, especially in caves, and it is not normally found in sand. |
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| Habitat | ||
| Epilithic on the shore and down to 5 m in the sublittoral. Favours low-lying rocks adjacent to sand. |
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| Recorded distribution | ||
| Generally distributed around the British Isles. |
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| Researched by | ||
| F. Bunker / C. Maggs |
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| Synonyms | ||
| Rhodochorton floridulum; Audouinella floridula |
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| Acknowledgements | ||
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Additional Photos
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| Close up of plants showing sand binding habit. Scale: Plant length approximately 2 cm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Large rocky outcrop dominated by Rhodothamniella floridula. Scale: n/a Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| View across eulittoral rock dominated by sand binding Rhodothamniella floridula. Scale: Picture width approximately 0.5 m Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Isolated clump of Rhodothamniella floridula in tray. Scale: With of clump approximately 2 cm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Irregular branching habitat of an individual axis. Scale: Length of axis approximately 1.5 cm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Individual axis showing multiple sinuate chloroplasts (3 to 8) per cell. Scale: Width of axis approximately 30 μm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Tetrasporangia at ends of branches (formed in winter only). Scale: Width of axis approximately 30 μm Location:Freshwater West, Pembrokeshire - Photographer:F. Bunker - Date:02/01/2002 - Identified By:F. Bunker - Verified By:C. Maggs | ||
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