Identification of asymmetrically winged samaras from the Western Hemisphere

Mirle, C. & R. J. Burnham (Museum of Paleontology, University of Michigan, Ann Arbor, MI 48109-1079, U.S.A.). Identification of asymmetrically winged samaras from the Western Hemisphere. Brittonia 51: 1-14. 1999.-A key is pre sented for use in identifying asymmetrically winged fruits (samaras) with e ither proximal or distal locules. It aids identification based on dispersed fruit morphology and can be used to identify undetermined extant herbarium specimens or fossil fruits to the correct extant family and genus. The 39 genera from II families (Aceraceae, Anacardiaceae, Fabaceae, Malpighiaceae, Phytolaccaceae, Polygalaceae, Polygonaceae, Rutaceae, Sapindaceae, Trigoni aceae, Ulmaceae) are distinguished on the basis of wing venation, size of f ruit, presence and position of attachment surface, presence and type of sub sidiary wings on the ovary wall, ornamentation, size and shape of the ovary , locule position, shape of locule cross section, style position and orname ntation, distinction between ovary wall and wing, and angle of attachment b etween individual samaras. The developmental origins of some of these featu res are discussed.