XVI International Botanical Congess

Arceuthobium americanum (dwarf mistletoe) is a parasitic plant. Its 'seed' lacks a seed coat, instead, the embryo and endosperm are enveloped by mucilaginous viscin cells. Viscin cells originate within the fruit as isodiametric cells which elongate as vacuoles accumulate at their distal ends. The endomembrane system produces a mucilage which passes though and is deposited outside of the primary cell wall. Cytochemistry reveals that the mucilage has a protein component and an insoluble carbohydrate component. The mucilage was probed with several lectins to determine a carbohydrate profile. Preliminary results indicate that galactose is the predominant mucilage carbohydrate. The mature, thickened viscin primary cell walls are helically-arranged, birefringent, and have a large cellulosic component.