Algae orders

The order Pennales is a proposed traditional subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. The valves may be linear or oval in shape, and usually bear bilaterally symmetrical ornamental patterns. These patterns are composed of a series of transverse lines (known as striae) that can appear as rows of dots when viewed with an optical microscope. Some pennate diatoms also exhibit a fissure along their longitudinal axis. This is known as a raphe, and is involve

Hibberdiales is an order of Chrysophyceae (golden algae).