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Sphondylothamnion multifidum (Hudson) Nägeli
Le Jolis
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RHODOPHYCEAE
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(many cleft whorled small bush)
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| Photo details | ||
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Plant collected from a cobble in a semi-exposed bay showing an opposite branching pattern. Scale: Plant length 7 cm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: |
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| Identification Notes | ||
| This species shows a wide variation in branching pattern. It generally grows in tufts up 5 to 20 cm high with main axes which branch in either an irregularly alternate or an opposite manner. The axes are composed of large ecorticate cells up to 600 µm in diameter from which issue a short whorl of short branches (giving a total diameter of 1 to 2 mm for axis and whorl branch). Between 2 to 6 branches are formed per whorl and these often occur in opposite pairs and themselves branch 1 to 3 times in an irregularly whorled dichotomous or trichotomous pattern. These whorl branchlets are filamentous and approximately 30 µm in diameter. Plants are crisp and ridged decaying rapidly on collection and are rose-pink or a slightly brown-red in colour. aracterising features: Gametophytes are dioecious with spermatangial heads formed on the last two orders of branching whorl branches (July) as globular swellings about 65 µm in diameter on the basal 1 or 2 cells of the branchlets. cystocarps (recorded July and September) develop on 2 nd order laterals or sub-terminally on whorl branchlets and are 140 to 600 µm in diameter when mature. Tetrasporangia form adaxially on the last two orders of whorl branchlets on the basal and supra-basal cells where they number 1 or 2 per cell and grow to 85 µm in diameter. Maggs & Hommersand, 1993 |
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| Confusion | ||
| Forms of S. multifidum with few sparse / short whorl branches can superficially resemble Halurus flosculosus but this species does not have whorl branches apart from those that develop terminally around the characteristic gametangia. Halurus equisetifolius has Gloss:whorl-branches which are >75 µm in diameter with a mucronate terminal cell compared to 30 µm in diameter with a bluntly rounded terminal cell in S. multifidum. Also, the whorl branches in H. equisetifolius are generally more closely spaced along the main axis than in S. multifidum and the plant is more robust and a darker red in colour. Where branching occurs in two opposite rows, there is scope for confusion with Antithamnion and Pterothamnion species, but these general have conspicuous gland cells which are absent in Sphondylothamnion. Also, Antithamnion and Pterothamnion species have plastids which are ribbon-like to filiform, whereas in S. multifidum they are discoid or bacilloid. |
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| Habitat | ||
| Growing on bedrock in shaded lower shore pools and sublittorally on upward facing surfaces to 30 m. This can be a conspicuous species in kelp forests and on mobile substrata including maerl. It is tolerant of some sand scour and occurs in a wide range of conditions from very sheltered to exposed. |
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| Recorded distribution | ||
| Occurring all around Ireland but predominantly a species of south and west Britain, although it occurs northwards to Cromarty. |
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| Researched by | ||
| F. Bunker |
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| Synonyms | ||
| Acknowledgements | ||
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Additional Photos
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| Plant collected from a cobble in a semi-exposed bay showing an opposite branching pattern. Scale: Plant length 7 cm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
| Close up of main axis showing arrangement of whorl branches. Scale: Axis diameter 300 µm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:09/06/2003 - Identified By:F. Bunker - Verified By: | ||
| Detail of main axis with 4 branches per whorl. Scale: Axis diameter 300 µm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:11/08/2003 - Identified By:F. Bunker - Verified By: | ||
| Plants collected from an exposed open coast in a kelp forest. Some branch ends were observed growing rhizoids for reattachment. Plant height (tallest) 8 cm Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:11/08/2003 - Identified By:F. Bunker - Verified By: | ||
| Detail showing irregularly alternate branching of plants collected from an exposed open coast kelp forest with two branches per whorl. Scale: Width of axial cells 240 µm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:11/08/2003 - Identified By:F. Bunker - Verified By: | ||
| Detail of paired and not very well developed whorl branches from a plant collected from an exposed open coast kelp forest. Scale: With of axial cells 240 µm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:11/08/2003 - Identified By:F. Bunker - Verified By: | ||
| End of a main branch of a plant showing branching structure whereby re-attachment or entanglement with other axes occurs (plant collected from an exposed open coast kelp forest). Scale: With of axial cells 120 µm. Location:St.Justinians, Pembrokeshire - Photographer:F. Bunker - Date:11/08/2003 - Identified By:F. Bunker - Verified By: | ||
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