Identify that alga:
Web-based key to genera -3: branched filaments with chloroplasts

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Colonies and coenobia
with sheath
without sheath  

flat plate

Colonies and coenobia : Cyanobacteria
with sheath

(under development)
 + chloroplast(s)

(under development)

non-flagellate cells
without case
(under development)
 in silica case
= diatoms
(under development)
flagellate cells

(under development)

no chloroplast:


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  Branched filaments Click on the thumbnail for a larger image

True branching (formed by lateral division of a cell)


False branching (not as above: formed by growth of end of a broken filament): seen mainly in Cyanobacteria


True Branching


Cells in main axis and branches different diameters (NB not the branches themselves)


Cells in branches all same diameter (but may taper towards ends):


Cells different diameters


Plant uniseriate (1 series of cells in each filament), chloroplasts present



Plant and chloroplasts green, enveloped in loose, slippery mucilage. Side branches much divided with terminal hairs, main axis cells same length whether or not they bear branches.


If branch-bearing cells are shorter, it is Draparnaldiopsis

Filament multiseriate (main axis)


Plant brown, olive-green or blue-green, smallest branches in whorls, enveloped in slippery mucilage

Batrachospermum: (Rhodophyta) "frog-spawn alga"

Cells same diameter


Filament multiseriate


 Plant green, macroscopic, forming a hollow branching tube

  Enteromorpha: more commonly known as a marine species

Plant grey-green or brown, filament multiseriate (more than 1 cell in width, except at tip), tough, wiry, with tapering branches and swellings (nodes) at intervals. Chloroplasts grey, disc-shaped, around periphery of cell.

a Rhodophyte

Cells arranged in series (usually single) in a broad sheath.Branching is false and cells have blue-green chloroplasts with clearly visible pyrenoids

  Asterocystis (Chroodactylon): Rhodophyte

Plant brown, olive-green or blue, cells without chloroplasts, branches sticking out at right angles to main axis: Cyanobacterium: see here for more.

Stigonema     Hapalosiphon

Filament uniseriate


Plant reddish or grey-green, chloroplasts disc shaped, branches without terminal hairs


Plant coarse-feeling, much-branched, with net-like chloroplast


Plant small, filaments short, chloroplasts disc-shaped, parietal, cells without bristles


Plant small, prostrate, chloroplasts disc-shaped, cells often with a sheathed bristle

  Coleochaete: other species are pseudoparenchymatous (forming a flat disc)

Branching usually sparse or moderate, ends of filaments bearing pointed cells or drawn into long multicellular hairs. No colonial mucilage. Chloroplast a green parietal band:

["Hair" refers to a cellular or multicellular extension to a filament: "bristle", "seta" and "pseudocilium" are non-cellular]

plant attached to surfaces

Stigeoclonium: this actually has 2 filament types, erect and prostrate (which attaches it to the substratum, but is not usually collected in field specimens)

plant epiphytic on other algae

    Branching repeated, with ends of filaments bearing pointed cells or drawn into long multicellular hairs: the whole colony contained in a firm, dense mucilage.

Filament irregular in thickness, cells tapering, each bearing a seta (hair) with a bulbous base



Filament composed of separate spherical cells in mucilage


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John Kinross