Spirodela polyrhiza


Spirodela polyrhiza is a species of duckweed known by the common names common duckmeat, greater duckweed, great duckmeat, common duckweed, and duckmeat. It can be found nearly worldwide in many types of freshwater habitat. It is a perennial aquatic plant usually growing in dense colonies, forming a mat on the water surface. Each plant is a smooth, round, flat disc 0.5 to 1.0 cm wide. It produces several minute roots. It also produces a pouch containing male and female flowers. The top part dies in the fall and the plant often overwinters as a turion.
S.polyrhiza is an ideal system for biofuels, bioremediation, and carbon cycling due to its aspects of fast-growing, direct contact with media, and smallest genome size. A comprehensive genomic study of S. polyrhiza was published in February 2014. The results provide insights into how this organism is adapted to rapid growth and an aquatic lifestyle.
S. polyrhiza, living in ponds and slow-moving water bodies, differs developmentally from terrestrial plants in morphology and physiology. It undergoes mainly vegetative growth called fronds in spring and summer, while switching into a dormant phase represented by turions in autumn and winter due to nutrition starvation and freezing temperatures. Turions could also be induced by the plant hormone ABA in the lab. Researchers reported that turions were rich in anthocyanin pigmentation and had a density that submerged them in liquid media. Transmission electron microscopy l of turions showed in comparison to fronds shrunken vacuoles, smaller intercellular space, and abundant starch granules surrounded by thylakoid membranes. Turions accumulated more than 60% starch in dry mass after two weeks of ABA treatment.

Distribution

As Lemna polyrhiza L., it is mainly found in the south and east of the British Isles. In Ireland it is found in counties Down, Antrim, and Londonderry.