XVI International Botanical Congess

The diagnostic characters of the simple thalloid liverwort Fossombronia cristula are difficult to observe from herbarium specimens using optical microscopy. To better observe these characters scanning electron microscopy is used. The dried plants were restored using the following protocol: (1) the plants were cleaned of debris, (2) soaked for 24 hours in 2% Tween, rinsed in dH2O, 3X at 30 minute intervals, (3) soaked in saturated Chloral Hydrate solution for four days, (4) fixed in weak chromo-acetic acid for 24 hours, (5) dehydrated through a graded ethanol series at one hour intervals, and (6) critical point dried using CO2 as the transition fluid. Comparisons of structural detail were made among FAA preserved plants (control), six month old dried plants, and 131 year old dried plants.