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Plumaria plumosa (Hudson) Kuntze
Le Jolis
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RHODOPHYCEAE
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(elegant soft feather weed)
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| Photo details | ||
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Plants on vertical north facing lower shore bedrock. Scale: Plant lengths approximately 5 to 7 cm. Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs |
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| Identification Notes | ||
| Plants grow in dense tufts, between 4 and 13 cm high, flattened in one plane and when submerged and viewed with a lens, branches have a feathery appearance. There are up 5 orders of irregularly alternately arranged branches with erect axes issuing from a single short basal axis 0.5 to 0.9 mm in diameter attached by a discoid holdfast. The feathery appearance of fronds is due to lateral branchlets that either are either unlimited or limited in length (' indeterminate' or ' determinate' ), borne in a distichous arrangement. The indeterminate laterals are borne in opposing pairs on every cell of the main axes with some being long and some short and all are strongly incurved. Long indeterminate laterals occur on alternate sides of axes at intervals of 2 to 3 (sometimes more) axial cells and the short ones are formed in between and increase in length along a series between the long indeterminate branches. Determinate laterals are borne in pairs on indeterminate laterals which increase in length along axes and are clothed in monosiphonous non-corticated branchlets tapering from 22 to 36 µm at the base to 14 to 16 µm at the apex. Plants are soft and flaccid and dull brown to purplish-red in colour. Other characterising features: Plants are dioecious. Specialised spermatangial branchlets develop on on all sides of ultimate branchlets, 4 to 5 cells in length and simple or branched. cystocarps are formed near the apices of determinate branches; they are about 180 µm in diameter, consisting of 3 to 5 lobes of different ages, each up to 140 µm across and and are surrounded by filamentous bracts. Tetrasporangia are 52 to 66 µm in diameter and are borne usually singly on the monosiphonous ultimate branchlets. Maggs & Hommersand, 1993 |
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| Confusion | ||
| Robust plants of Plumaria plumosa could be confused with P. gunneri but the main apices have a different branching pattern. Whereas P. plumosa forms an indeterminate lateral branch on every axial cell, in P. gunneri, these branchlets are formed every 2 to 3 cells. In P. plumosa, the ' determinate laterals' are single celled and ecorticate whereas in P. gunneri, they are several cells wide and develop cortication. |
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| Habitat | ||
| Plants are epilithic and occur on bedrock and small algae, rarely on Laminaria hyperborea stipes. The typical habitat is vertical or overhanging shaded bedrock such as occurs on north facing slopes or in caves. Occasionally found in mid to lower shore pools and subtidally. |
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| Recorded distribution | ||
| Generally distributed and very common around the British Isles. |
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| Researched by | ||
| F. Bunker |
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| Synonyms | ||
| Acknowledgements | ||
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Additional Photos
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| Plants on vertical north facing lower shore bedrock. Scale: Plant lengths approximately 5 to 7 cm. Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Whole plant in tray. Scale: Plant height 5.5 cm Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Part of thallus illustrating the complanate nature and the irregularly alternate branching pattern. Scale: Height of branch shown 1.5 cm Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Irregularly alternate branching pattern with the main axes bearing a regular series of shorter branches. Width of axis 180 µm. Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Apex of side branch showing paired ecorticate monosiphonous branchlets occuring on every cell. Scale: Width of plant at apex 500 µm. Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
| Tetrasporangia born on ecorticate monosiphonous last-order branchlets. Scale: Diameter of tetrasporangia 50 µm. Location:West Angle Bay, Pembrokeshire - Photographer:F. Bunker - Date:30/09/2003 - Identified By:F. Bunker - Verified By:C. Maggs | ||
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