RADTKE, MEGHAN G.1*, KATHLEEN B. PIGG1, and WESLEY WEHR2. 1Department of Plant Biology, Box 871601, Arizona State University, Tempe, AZ, 85287-1601; 2Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, 98195. - Fossil Corylopsis and other Hamamelidaceae-like leaves from the middle Eocene flora of Republic, Washington, USA.
A fossil leaf of Corylopsis Sieb. & Zucc., (Hamamelidaceae;
Saxafragoid clade) and several other Hamamelidaceae-like leaves are
described from the middle Eocene (49-50 MA) Republic flora of eastern
Washington State, USA. The fossil Corylopsis leaf is similar to
several extant species, particularly with the presence of prominent
agrophic veins and ladder-rung-like tertiaries at right angles to the
secondaries. The leaf is 1.9 cm wide, of incomplete length, with an
asymmetrical base. Teeth are concave apical, straight basal, with
simple apices. Several other Hamamelidaceae-like leaves present in the
Republic flora are simple, symmetric, range from 2.1 to 8.7 cm in
length, from 0.9 to 4.3 cm in width, have a L/W ratio of 2.0 to 2.3
and are generally elliptic in shape. Bases are typically asymmetric
and cordate to rounded. Leaf apices are not preserved. Venation is
craspedodromous with secondary veins produced alternately from the
midvein. Compound agrophic veins varying from 1 to 2 are produced by
the secondaries. Ladder-rung-like tertiary veins are formed at right
angles to the secondaries. Tertiaries and quaternaries comprise
usually 5-sided areoles containing 5th order veins. When visible,
teeth are generally concave apical, straight basal, with a simple
apex. Today Corylopsis, an ornamental shrub commonly called
"Winter Hazel", is known only from the Himalayas to Japan,
but was more widely distributed in the past. The fossil record of
Corylopsis is based primarily on seeds that occur from the
Eocene throughout much of the Tertiary in Europe, the Eocene of
eastern North America, and from one previous report of a leaf from the
Eocene of Alaska. The presence at Republic of Corylopsis and
other Hamamelidaceae-like leaves including the previously described
Langeria magnifica demonstrates a high diversity in this group
during the middle Eocene of western North America.
Key words: Corylopsis, Eocene, fossil leaf, Hamamelidaceae, North America