RUTACEAE ^ 49 



RUTACEAE 

 The Rue Family 



The rue family consists of trees or shrubs, which are made 

 aromatic hf secreting glands In the foliage. The leaves are for 

 the most part digltately or pinnately compound, and the leaflets 

 are not equilateral. The flowers are perfect and polygamous or 

 dioecious. The calyx consists usually of 3 to 5 lobes or sepals, 

 which rarely may be w^antlng, and there are 3 to 5 petals. The 

 stamens may be either the same number as the petals or twice 

 as many, and the ovary consists of 1 to 5 or more free or united 

 carpels. The fruit Is variable and may be a follicle, a capsule, 

 a samara or a drupe. 



This large family of more than 100 genera and nearly 1,000 

 species occurs most abundantly In South Africa and Australia. 

 Its 2 North American shrubby genera are both native in Illinois. 



Key to the Shrubby Genera 



Shrubs armed with spines, the leaflets more than 3 



Zanthoxylum 



Shrubs not armed with spines, the leaflets 3 per leaf Ptelea 



ZANTHOXYLUM Linnaeus 

 Prickly-Ash 



The prickly-ashes are shrubs or trees, usually prickly and 

 with aromatic bark, that bear alternate, usually pinnate leaves 

 often provided w^ith stipular prickles. The flow^ers are mostly in 

 cymes or panicles and are perfect and dioecious or polygamous. 

 The sepals may be 3 to 5, or sometimes w^antlng, and usually 

 are more or less united. There are 3 to 10 petals and 3 to 5 

 stamens. The pistils, which are only rudimentary in staminate 

 flowers, number 1 to 5 and develop into 1-celled and usually 

 1-seeded follicles. The seeds are oblong, black, and shiny. 



Among about 150 species, which are natives of temperate 

 and near-tropical regions, only 4 occur within the boundaries 

 of the United States and only 1 In Illinois. 



ZANTHOXYLUM AMERICANUM Miller 



Prickly-Ash Toothache-Tree 



The Prickly-Ash, fig. 35, Is a much-branched, upright shrub 

 generally 4]/i to 10 but sometimes as much as 18 feet high, with 



