Wayne's Word Index Noteworthy Plants Trivia Lemnaceae Biology 101 Botany Scenic Wildflowers Trains Spiders & Insects Search Sierra Nevada Jan. 2015 Part 3      Home        Part 1        Part 2        Part 3        Part 4        Part 5        Part 6        Part 7        Part 8   The Walker River Frozen Over With Layer Of Ice This roaring river north of Bridgeport, CA is completely frozen over with a thick layer of ice--a testimonial to the freezing temperatures at this time of the year. A nearby tributary contains a remarkable liverwort and a very cold-tolerant duckweed (Lemna trisulca) that survives under the ice layer in these freezing waters. A Liverwort & Duckweed In Frozen Creek Near The Walker River A creek frozen over near the Walker River north of Bridgeport. The white arrow points to a population of liverworts. Also living in this creek is a population of the duckweed Lemna trisulca. The following images were taken of this liverwort & duckweed colony in October 2011. Liverwort in a creek near the Walker River north of Bridgeport. It resembles on-line images of the thalloid liverwort Conocephalum conicum. It has a well-marked hexagonal surface on the upper thallus. In the center of each hexagon is a minute pore. These features are barely visible in the above image. The plant was growing in shallow water of a marsh along a slow moving creek with dense population of Lemna trisulca. Highly magnified view of polygonal surface on the upper (dorsal) side of liverwort thallus. The polygons delineate the internal air chambers. In the center of each polygon is a rimmed pore. Each pore leads into an air chamber containing columns of photosynthetic cells and facilitates in gas exchange. Unlike the stomata of vascular plants which close in dry weather, the air pores of liverworts remain open all the time. Liverworts cannot control their water loss (transpiration) through the pores. They must live in shady, moist areas where they can imbibe water, and where there is sufficient water for their swimming sperm to reach the egg. Magnification 400x. Lemna trisulca (lower) and liverwort resembling Conocephalum conicum. Dense colonies of these plants were growing intermixed in the shallow water of a marsh along a creek near the Walker River (north of Bridgeport).   See The Wayne's Word Duckweed (Lemnaceae) Home Page   All images on this page copyright © W.P. Armstrong