This species ranges from 2-25 cm in height in our flora and commonly forms unattached matts in salt marsh habitat (Image A), although individuals attached to various algae can be found in more estuarine areas and are more typical in Europe (Image B). In Canadian specimens branching is sparse, typically at ~90o angles to the bearing axis (Image C), while some individuals can display numerous short (‘varia-type’) branchlets (Image D). Axes are typically uniseriate, at times biseriate, with cells 12-50 µm wide by 25-70 µm long each containing multiple discoid plastids (Image E). Reproductive structures were equivocal in Canadian specimens with putative unilocular initials observed (fungal infection?; Image F) and structures that looked like propagules (Images G, H) observed.
This species is limited to sheltered sites, typically estuarine and salt marsh, in our flora with only a few genetically verified records from CN, Bay of Fundy (NB), and southern NL. We also have verified specimens from Norway. In addition to being attached to various algae (eg. Ascophyllum nodosum (Linnaeus) Le Jolis, Fucus spp.), this species can form extensive unattached matts (Image A). Collected from upper intertidal to shallow subtidal (3 m) in our flora. This species can be distinguished from Pylaiella washingtoniensis Jao, which produces rhizoids, tends to form a rope-like habit, and has more acute angles between branches and their bearing axis. Pylaiella littoralis (Linnaeus) Kjellman typically exhibits opposite branching, occasionally unilateral, but again at acute angles to the bearing axis. Confident identification requires molecular tools.
Image A. Unattached uppermost intertidal matts tangled among salt marsh plants and drift algae (‘Cottonii’ Creek, near Letete, NB; GWS045015).
Image B. Attached individuals on a drift Fucus (Station Dorm Beach, Espegend, Norway; GWS038076).
Image C. Branches sparse and typically at ~90o angles to the bearing axis (GWS045105).
Image D. Short branchlets (‘varia-type’) also typically at ~90o angles to the bearing axis (uppermost intertidal from grass stolons, ‘Cottonii’ Creek, near Letete, NB; GWS045106).
Image E. Axes are typically uniseriate, but can be biseriate at times; cells have multiple parietal discoid plastids (GWS045105).
Image F. Putative unilocular sporangium initial (or infection?) (GWS045106).
Image G. Putative vegetative propagule (GWS045106).
Image H. Putative vegetative propagule (GWS045106).
Seaweed of Canada 