RUTACEAE. 



161 



ZANTHOXYLUM. Prickly Ash. 

 (Family Rutaceae). 



Small trees or shrubs, aromatic 

 or pungently acrid, usually armed 

 with detachable prickles which 

 sometimes occur paired at the 

 nodes: deciduous. Twigs moder- 

 ate ' or stout, subterete: pith 

 rounded, continuous, very creamy 

 white. Buds moderate, super- 

 posed, sessile, globose, woolly and 

 indistinctly scaly. Leaf-scars al- 

 ternate, broadly triangular or 3- 

 lobed, little raised, sometimes with 

 a conspicuous articular mem- 

 brane: bundle-traces 3: stipule- 

 scars lacking. Winter-character 

 references under Evodia. 



The strong prickles beside the 

 leaf-scar in Zanthoxylum present 

 a puzzling question as to their 

 morphology. If they represent 

 stipules, they should be called 



spines: if they are superficial outgrowths of the cortex, they 

 are truly prickles. Position is not a safe guide. The pungent 

 outgrowths of gooseberry and rose are prickles: they are sti- 

 pules in the locust, and, like other stipules, are connected 

 with the vascular system of the stem at least in their early 

 stages. They are believed to be prickles in Zanthoxylum. 



1. Prickles broad and acuminate. (1). Z. Bungei. 

 Prickles not acuminate even when widened. 2. 



2. Nodal prickles often widened: articular-membrane 



conspicuous: buds red-rusty. (2). Z. americanum. 



Prickles not greatly dilated nor articular-membrane 



developed: buds glabrous. (3). Z. Clava Herculis. 



