A bright scarlet seaweed up to 30 cm in length with branching fronds. The branching occurs alternately along the fronds and becomes more frequent towards the tips. The general appearance of these seaweeds can greatly vary from very compact and closely branched to a much broader appearance with widely separated branching. The tips are incurving and ultimate branching occurs only to one side, giving a distinctive feathery or comb-like appearance.The variety Plocamium cartilagineum uncinatum displays reflexed rather than incurved branching at tips but is less common in British Isles and more frequent in Mediterranean.

Thallus grows from a discoid holdfast to form a frond with distinctive pectinate branching. The frond, up to 15 cms long, is generally flattened and the profuse sympodial branching. The final branchlets are comb-like in groups of 2 - 6 in regular sequence, each group alternating with a similar group on the other side. Gametangial and tetrasporangial plants are similar. Sphaerococcus coronopifolius and Callophyllis cristata are similar but do not show the distinctive branching pattern. Recent studies have shown that there are actually four species of Plocamium in Northern Europe, P. cartilagineum, Plocamium subtile, Plocamium nanum and Plocamium maggsiae (Saunders & Lehmkuhl, 2005).

Azores Exclusive Economic Zone, Belgian Coast, Boulogne, Pointe de la Creche, Cap Gris Nez, De Haan, Dutch Exclusive Economic Zone, European waters (ERMS scope), Irish Exclusive economic Zone, Koksijde, Madagascar, Mediterranean Sea, Oostduinkerke, Pointe du Nid de Corbet, Pointe du Riden, Swedish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, Wimereux

All around the British Isles including the Shetlands. Europe: Mediterranean, Azores, Portugal, Atlantic coast of Spain and France, Norway, Faroes and Iceland. Further afield: Pacific America from Alaska to California, Chile and the Galapagos Islands, Canary Islands and Australia. Widespread in temperate seas.

Known from the nearshore.

Depth range based on 414 specimens in 1 taxon.
Water temperature and chemistry ranges based on 42 samples.

Environmental ranges
  Depth range (m): 0 - 33.05
  Temperature range (°C): 11.054 - 12.270
  Nitrate (umol/L): 4.757 - 6.816
  Salinity (PPS): 35.008 - 35.343
  Oxygen (ml/l): 6.095 - 6.346
  Phosphate (umol/l): 0.335 - 0.485
  Silicate (umol/l): 2.311 - 3.727

Graphical representation

Depth range (m): 0 - 33.05

Temperature range (°C): 11.054 - 12.270

Nitrate (umol/L): 4.757 - 6.816

Salinity (PPS): 35.008 - 35.343

Oxygen (ml/l): 6.095 - 6.346

Phosphate (umol/l): 0.335 - 0.485

Silicate (umol/l): 2.311 - 3.727
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

 Grows on rocks in shallow water and as an epiphyte on other seaweeds e.g. on the stipe of Laminaria hyperborea.

Common. Epilithic and epiphytic in the lower littoral and sublittoral to 30 m or more.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 11
Species With Barcodes: 1

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 15
Species With Barcodes: 1