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Lomentaria clavellosa (Turner) Gaillon
Le Jolis
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RHODOPHYCEAE
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(jointed club podweed)
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| Photo details | ||
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Whole plant of sheltered water form in tray. Scale: Plant length 5 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 | ||
| Erect thalli growing to 40 cm long and showing much variation in extent of branching, degree of flattening and frond texture. Axes are hollow, grow to 4 mm in diameter and tend to narrow towards the base which does not have branches and attaches via a small disc. Branching is in one plane, up to 4 times pinnate and branches are terete or flattened tapering towards the base and apex. Sometimes, an irregular arrangement of radial branches occurs and in less exposed situations, luxuriant specimens can be found clothed with many adventitious branches. Plant texture ranges from soft to slightly cartilaginous and colour from dark brownish to purple-red to pink (often bleaching in summer). Other characterising features: Plants from exposed coasts tend to be flattened and pyramidal in shape with a neat arrangement of pinnate branches. Plants from sheltered coasts tend to be soft, terete and are often luxuriously branched with adventitious branches masking the pinnate arrangement. Plants are dioecious with spermatangia produced in pale sori in younger parts (not recorded in the British Isles). cystocarps are external and conical in shape, 375 to 550 µm in diameter and have a thick cortical pericarp plus a prominent pore (reported January and April to November). Tetrasporangia are 45 to 60 µm in diameter and occur in cortical depressions in younger branchlets (occurring throughout the year). Sectioning reveals the presence of medullary filaments, which are 12 to 18 µm in diameter forming a network and are closely compacted at branch bases into a 3 to 5 layered plug of large rounded cells. Irvine, 1983 |
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| Confusion | ||
| Small distichous plants may be confused with Lomentaria orcadensis but apical branches are approximately 500 µm apart and 500 µm broad in L. clavellosa as opposed to 2 to 4 mm apart and 1 mm broad. Soft delicate plants can resemble Gliosiphonia capillaris but this species has internal cystocarps and tetrasporangia are confined to an encrusting phase. Sterile plants of G. capillaris do not have the discrete medullary filaments typical of Lomentaria clavellosa. |
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| Habitat | ||
| Epilithic and epiphytic found in the lower littoral in shady places in and out of pools and in the sublittoral to at least 24 m in areas moderately to extremely exposed to wave action. |
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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 | ||
| Acknowledgements | ||
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Additional Photos
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| Whole plant of sheltered water form in tray. Scale: Plant length 5 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Close up of sheltered water form branching (terminal branches with tetrasporangia). Scale: Approximate width of photograph 0.7 cm. Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Terminal branchlet with tetrasporangia in depressions. Scale: Length of branchlet approximately 4 mm Location:Fal, Cornwall - Photographer:F. Bunker - Date:29/08/2001 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Luxuriously branched plant from moderately exposed silted bedrock (2 m below chart datum). Scale: Plant length 28 cm. Location:St. Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
| Close up of branch of a plant from a moderately exposed silted bedrock (2 m below chart datum). Scale: Plant length 6 cm. Location:St. Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
| Urceolate cystocarps from plant collected from a moderately exposed silted bedrock (2 m below chart datum). Scale: Cystocarp width 420 μm. Location:St. Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
| Flattened plant with a neat, pinnate arrangement of branches from an exposed open coast situation. Scale: Plant length 8 cm Location:St. Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
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