CLASS XXIII. ORDER II. 405 



416. XANTHOXYLUM. 

 Xanthoxylum Fraxineum. Prickly Ash. 



American Medical Botany, PI. lix. 



Prickly; leaves pinnate; leafets ovate, subentire, 

 sessile, equal at base; umbels axillary. 



The branches of this shrub are covered with strong, sharp 

 prickles, arranged without order, most frequently in pairs, at the 

 insertion of the young branches. Leaves pinnate, the common 

 petiole sometimes unarmed and sometimes prickly on the back. 

 Leafets about five pairs, with an odd one, nearly sessile, ovate, 

 acute, with slight vesicular serratures, somewhat downy under- 

 neath. The flowers appear in April and May, before the leaves 

 are expanded. They grow in sessile umbels about the origin of 

 the young branches, are small and greenish. I have observed 

 them of three kinds, making the shrub strictly polygamous. In 

 the staminiferous flower, the calyx is five leaved, leaves oblong, 

 obtuse, erect. Stamens five, with subulate filaments and sagit- 

 tate four celled anthers. In the place of the pistils are three or 

 four roundish corpuscles supported on pedicels from a common 

 base. The perfect flowers growing on the same plant have the 

 calyx and stamens like the last ; the germs are three or four, 

 pedicelled, and having erect, converging styles nearly as long as 

 the stamens. The pistiliferous flowers grow on a separate shrub. 

 Calyx smaller and more compressed. Germs about five, pedi- 

 celled ; styles converging into close contact at top, and a little 

 twisted. Stigmas obtuse. All the flowers are destitute of co- 

 rolla. Each fertiie flower produces an umbel of as many stipi- 

 tate capsules as there were germs in the flower. These cap- 

 sules are oval, covered with excavated dots, varying from green 

 to red, two valved, one seeded ; seed oval, blackish. — Woods, 

 Medford. — April, May. — Perennial. 



The rind of the capsules has an agreeable lemon-like scent. 

 The bark is pungent, and is used in rheumatism. 



417. ACER. 



Acer rubrum. L. Swamp Maple. Red 3Iaple. 



Leaves palmate-five lobed, unequally toothed, pu- 



