McCandless survived for approximately 113 days in the Alaskan wilderness, foraging for edible roots and berries, shooting an assortment of game—including a moose—and keeping a journal. Although he planned to hike to the coast, the boggy terrain of summer proved too difficult, and he decided instead to camp in a derelict camping bus left behind by a road construction company. In July he tried to leave, only to find the route blocked by the Teklanika river raging with snow-melt. On July 30, McCandless wrote a journal entry which read, "Extremely Weak. Fault Of PotSeed". Based on this entry, Krakauer hypothesized that McCandless had been eating what he thought was the roots of an edible plant, "Hedysarum alpinum", commonly known as wild Eskimo potato, which are sweet and nourishing in the spring but become too tough to eat in the summer, perhaps forcing McCandless to eat the H. alpinum's seeds instead. Krakauer first speculated that the seeds were actually from "Hedysarum mackenzii", or wild sweet pea, instead of the Eskimo potato, which contained a poisonous alkaloid, possibly swainsonine (the toxic chemical in locoweed) or something similar. In addition to neurological symptoms, such as weakness and loss of coordination, the poison causes starvation by blocking nutrient metabolism in the body. However, Krakauer later suggested that McCandless had not confused the two plants and had in fact actually eaten "H. alpinum". Krakauer had the "H. alpinum" seeds tested for toxins and, through tests on "Hendysarum alpinum", it was discovered that it contained an unidentifiable form of toxin.