Subsistence horticulturalists learn considerable local ecological knowledge by early adulthood. We investigate the relationship between children’s family environments and learning of their plant environment. In a rural village in Dominica, West Indies, children of ages four through 17 (N = 51) participated in a “plant trail” along a route containing 50 core local plants marked for identification. Plants in question resulted from village adults’ freelists on members of local plant domains found via nominal group technique (i.e., trees, staple foods, vegetables, condiments, medicines, and ornamentals). Individual children’s ethnobotanical knowledge was assessed through proper plant identification with a local term. Findings indicate that children learn botanical domains differentially. They identify trees and staple crop plants early in life. As they develop, they learn other plant domains, and trees and staples decrease in proportion to total ethnobotanical knowledge. Boys retain a larger proportion of tree knowledge, as tree care is part of the masculine labor division. Children’s, especially girls’, proportion of medicinal plant knowledge grows steadily into adulthood. As predicted, children with homes in extended family compounds demonstrate more ethnobotanical knowledge than children whose neighbors are not close kin. Contrary to predictions, a father’s presence in the household is not an indicator of the children’s plant identification ability. Having younger siblings predicts learning more plants. Trees form a smaller proportion of total plant knowledge for family-compound-living children and those with lower birth order, who tend to have greater overall ethnobotanical knowledge. Ethnobotanical learning relates to gender, birth order, and extended kin access.