Heracleum maximum, also known as Cow parsnip, has 136200 seeds per pound. This plant is native to North America; in southwest Oregon it thrives in riparian areas, seasonally wet areas, and forest edges, and grows at a range of elevations. 
Seed treatment reccommendations: Direct sowing is recommended, though scarifying the seed with sandpaper or a file may improve germination rates. Sow in fall or stratify under cold moist conditions for 2-4 weeks before spring sowing.