RUTACEAE 151 



smooth, gray or brownish bark and smooth branches and 

 branchlets armed, at the base of each leaf, with a pair of 

 straight, sharp spines, which are persistent and much flattened 

 at the base. The odd-pinnate leaves, which are 3 to 10 inches 

 long, consist of 5 to 11 leaflets set oppositely in pairs along the 

 rachis on very short stalks. The narrowly to broadly ovate 

 leaflets, ^ to 3 inches long and ]/i to 1^ inches wide, taper 

 gradually to the apex, where they are obtuse and notched, but 

 at the base they are oblique and either narrowed or rounded. 

 The margin is entire or crenulate, and the surface, pubescent 

 at first, becomes smooth or nearly so above and remains pu- 

 bescent beneath. The petiole and rachis are sometimes prickly. 

 The flowers, which appear before the leaves, stand in small, 

 axillary clusters on the branches of the previous season. They 

 are dioecious and small, the staminate being about one-six- 

 teenth inch in diameter. The fruit, which matures in August 

 and September, is a reddish, globose or ellipsoid, 1-seeded cap- 

 sule about ]4, inch long, with a pitted surface. It is strongly 

 aromatic, and the seeds are black and shining. 



Distribution. — The Prickly-Ash is a shrub which prefers 

 low woods, especially those growing on flood plains and along 

 banks of streams. In such situations it is distributed from Que- 

 bec and Ontario to North Dakota and south to Georgia and 

 Oklahoma. In Illinois, it is a widely distributed and frequently 

 observed shrub throughout the northern two-thirds of the 

 state, but southward it is seldom or rarely encountered. The 

 most southern Illinois records are Tunnel Hill in Johnson 

 County and Murphysboro in Jackson County. 



PTELEA Linnaeus 



Hop-Tree Shrubby Trefoil 



The hop-trees are unarmed shrubs or trees with alternate 

 or, rarely, opposite, 3-foliate leaves, the leaflets of which are 

 entire or toothed and translucently dotted. The polygamous 

 flowers are produced in corymbose or paniculate cymes and 

 bear 4, 5 or, rarely, 6 sepals and the same number of greenish 

 or yellowish-white petals. There are 4, 5 or, rarely, 6 stamens, 

 which are imperfect in the pistillate flowers. The ovary con- 

 sists of 2 or 3 united carpels, and the fruit is a 2-celled or, 

 rarely, 3-celled samara with reticulated wings. 



