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Soft-Bodied Stream Algae of California

Species name:

Nostoc verrucosum Vaucher ex Bornet et Flahault

species photo 1
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Nostoc verrucosum photo


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Colony olive-green or brown, initially solid, spherical or hemispherical, but subsequently becoming more hollow, bullate, warty, typically 3-5 cm, but may reach 10 cm (Fig. A, courtesy of Melissa Mathis). Cells 3-3.8 µm wide, short barrel-shaped. Filaments flexuous, usually densely entangled towards the colony periphery, but less so towards the centre (Fig. B). Sheath yellow-brown, thick; individual sheaths distinct towards the periphery, colorless and diffluent towards the centre. Heterocysts subspherical, 4.8-6 µm wide. Akinetes ellipsoidal, 5-5.2 µm wide, 7-8 µm long; yellow-brown in color with smooth walls (Fig. C). Fig. D shows germination of hormogonia.