Date of this Version
Elowsky, C.G., I.E. Jordon-Thaden, and R.B. Kaul. 2013. A morphological analysis of a hybrid swarm of native Ulmus rubra Muhl. and introduced U. pumila L. (Ulmaceae) in southeastern Nebraska. Phytoneuron 2013-44: 1–23. Published 10 July 2013. ISSN 2153 733X
The parental species and hybrid swarm of native Ulmus rubra Muhl. and the introduced, naturalized and weedy U. pumila L. were investigated in a 65-km transect in Lancaster, Saunders, and Butler counties in Nebraska. Thirty-two trees of U. rubra, 32 of U. pumila, and 50 of the hybrid swarm were sampled for leaves and buds and subsampled for flowers and fruits. Leaves were measured for petiole length, blade length, width, primary and secondary teeth per cm, number of secondary teeth per primary tooth, and texture. Buds were scored for color and distribution of trichomes. Flowers were sampled for stamen counts and pollen size. Fruits were measured for length, width, and color and distribution of trichomes. Statistically significant differences (PUlmus × intermedia Elowsky.