GENUS 2. 



RUE FAMILY. 



445 



i. Ptelea trifoliata L. Three-leaved Hop-tree. Shrubby Trefoil. Fig. 2693. 



Ptelea trifoliata L. Sp. PI. 118. 1753. 



A shrub or small tree, with a maximum 

 height of about 20 and trunk diameter of 

 6'. Leaves long-petioled, 3-foliolate, pubes- 

 cent when young, glabrate when old, or 

 sometimes persistently pubescent ; leaflets 

 ovate or oval, 2'-$' long, sessile, crenulate, 

 acute or obtuse, the lateral ones somewhat 

 oblique, the terminal one more or less cu- 

 neate at the base; flowers about 5" broad, 

 in terminal compound cymes; odor disa- 

 greeable; sepals \" long, obtuse; petals 

 about 3" long, oblong; samara 8" -9" in 

 diameter, the wing membranous and reticu- 

 lated, emarginate, tipped with the minute 

 persistent style or this finally deciduous. 



In woods, Connecticut to Florida, west to 

 southern Ontario, Minnesota, Kansas and 

 Mexico. Consists of many trivially different 

 races. The fruit is bitter and has been used 

 as a substitute for hops. The foliage has an 

 unpleasant odor. Wood light brown ; weight 

 per cubic foot 43 Ibs. Ague-bark. Quinine- 

 tree. Pickaway-anise. Prairie-grub. Wafer-ash. Swamp-dogwood. Wingseed. June. 



Ptelea tomentosa Raf. (P. trifoliata mollis T. & G.) is a very pubescent race, ranging from 

 North Carolina and Georgia to Indiana and Durango. 



The common rue, Ruta gravbolens L., a native of Europe, has escaped from cultivation in 

 several localities in our range. It is a heavy-scented herb or partially woody plant and differs from 

 our other representatives of the Rue family in the perfect flowers, the 4-s-lobed ovary and the 

 lobed, several-seeded capsule. 



Family 68. SIMAROUBACEAE DC. Bull. Soc. Philom. 2: 209. 1811. 



AILANTHUS FAMILY. 



Trees or shrubs, with bitter bark, and mainly alternate and pinnate not punc- 

 tate leaves. Stipules minute or none. Inflorescence axillary, paniculate or race- 

 mose. Flowers regular, dioecious or polygamous. Calyx 3-5-lobed or divided. 

 Petals 3-5. Disk annular or elongated, entire or lobed. Stamens of the same 

 number as the petals, or twice as many ; anthers 2-celled. Ovaries 2-5. or single 

 and 2-5-lobed, i-5-celled ; styles 1-5. Seeds generally solitary in the cells; em- 

 bryo straight or curved. 



About 30 genera and 150 s-pecies, natives of warm or tropical regions, distinguished from 

 RUTACEAE mainly by their non-punctate foliage. 



i. AILANTHUS Desf. Mem. Acad. Paris, 1786: 265. pi. 8. 1789. 



Large trees, with odd-pinnate leaves, and terminal panicles of greenish-white polygamo- 

 dioecious flowers. Calyx short, s-cleft, the lobes imbricated. Petals 5, spreading, valvate. 

 Disk lo-lobed. Staminate flowers with 10 stamens inserted at the base of the disk. Pistillate 

 flowers with a deeply 2-s-cleft ovary, its lobes flat, cuneate, i-celled, and 2-3 stamens. Ovules 

 solitary in each cavity. Samaras 2-5, linear, or oblong, membranous, veiny, i-seeded at the 

 middle. Seed compressed; cotyledons flat, nearly orbicular. [From the Chinese name.] 



Three species, natives of China and the East Indies. The following typical one has become 

 widely naturalized in eastern North America. 



