Lupinus spp. and Alnus crispa subsp. sinuata are the first plants to look healthy and grow rapidly on cold raw mineral deposits exposed through glacier recession. Lupin causes associated willows, grasses and fire-weed to bloom and to grow several times as fast as plants growing separately. Young cottonwood [Populus sp.] trees surrounded by Alders grow about 3 times as fast as those living away from Alders. The root nodules on the Alders are thought to bring this about by the symbiotic fixation of atmospheric N, in the same way as lupin and other legumes. A field experiment has been set up in Glacier Bay National Monument to find out exactly how Alder causes this stimulation.