Psychopterys rivularis. a. Flowering branch. b. Base of petiole to show stipules. c. Flower. d. Petal laid flat. e. Anthers, abaxial view (left) and adaxial view (right). f. Samara, abaxial view. g. Nut of samara with lateral wings cut away, lateral view to show dorsal wing. h. Intact embryo. i. Enbryos in cross-section (left) and longitudinal section (right). Scale bar equivalents: a, 4 cm; b, 4 mm; c, 5 mm; d, 4 mm; e, 2 mm, f, g, 2 cm; h, i, 5 mm. Based on: a–e, Sinaca C. 57, WIS; f, g, Ibarra M. 603, MICH; h, i, Ibarra M. 3388, TEX. Drawn by Karin Douthit. First published in Contr. Univ. Michigan Herb. 25: 133. 2007; reproduced with permission of the authors.