Notes on Rutaceae—V. Species characters in Ptelea and Taravalia 
Percy WILSON 
The genus Ptelea as understood by Linnaeus, 1753, comprised 
two species, P. trifoliata L. from Virginia, and P. viscosa L. from 
India. The second species, was, however, later referred to 
Dodonaea, a genus of the Sapindaceae which has samaroid fruits 
resembling those of Ptelea. 
In the recent issue of the North American Flora, three species 
of Ptelea are recognized, two of which are regarded by some authors 
as varieties of P. trifoliata L. The characters used to separate 
these species cannot always be depended upon as there are various 
intermediate forms. 
A large number of specimens of Ptelea have been examined 
in various herbaria, including types or cotypes of nearly all the 
published species, and an excellent opportunity for a com- 
parative study of living plants of P. trifoliata L. has been afforded 
at the New York Botanical Garden, where many individuals of 
this species are under cultivation. These show great variation 
in their leaflets, color of bark, and form and size of the samaras, 
which vary from obovate to elliptic or suborbicular and are one 
to three centimeters in diameter. (See FIGURE.) The flowers are 
essentially alike except in size. Although the number of petals has 
sometimes been used as a character for distinguishing species, it is 
not uncommon to find flowers with both four and five petals in 
the same species, and often on the same branches. 
Ptelea Baldwinii T. & G. is represented in the Torrey her- 
barium by a small specimen collected by Baldwin at “St. Johns, 
E. Florida,” and P. angustifolia Benth. is illustrated by a drawing 
and fragments from the type. While there is a slight difference in 
the form of their leaflets, the specimens undoubtedly represent 
one species. 
Of the large number of species and varieties of Ptelea which 
have been described within the past few years, by several authors, 
in the majority of cases from single specimens examined, some 
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