a. Flowering branch. b. Distal portion of petiole enlarged to show glands. c. Unit of the inflorescence enlarged to show spreading bracts and bracteoles, and flower bud with one large gland on each lateral sepal. d. Flower, posterior petal uppermost. e. Stamens, abaxial view (left) and adaxial view (right). f. Gynoecium. g. Immature samara. Scale bar equivalents:
a, 4 cm; b, 4 mm; c, d, 1 cm; e, f, 2 mm; g, 1.3 cm. Based on: a–c, Prance 6675, MICH; d–g, Killeen 2750, MICH. Drawn by Karin Douthit. First published in Contr. Univ. Michigan Herb. 17: 47. 1990; reproduced with permission of the author.