Louise Erdrich’s Love Medicine, a sort of novel-in-stories that unflinchingly paints a portrait of Native American life in the modern world, opens with a beautifully elaborate family tree: the names get progressively more Catholic, the adoptions and marriages and remarriages more convoluted, as the generations pass. It’s a fitting way to begin this collection. Almost every person on the tree is featured either as a narrator or as a protagonist of one of the stories, but in my mind the three members of the oldest generation mentioned are the real heroes of Love Medicine. The lives of Nector Kashpaw (introduced in “Wild Geese” as a brash young tribesman), his future wife Marie Lazarre (still a teenager in “Saint Marie”), and their sometime ally Lulu Lamartine (who comes of age in “The Island”) are chronicled in full, from adolescence to old age, and it’s their obsessions and fatal flaws that ultimately give the book wings. Love Medicine has a rocky start: its younger characters, not nearly as complex or engaging as their grandparents, open the collection in a less-than-impressive introductory sequence. But the later stories are beautifully enough rendered to do their subject, the Ojibwe nation, proud.