ROSACEAE 57 



9. Calyx often persistent on the fruit. P. micromalus. 



Calyx absent from fruit. (Siberian crab). P. baccata. 



10. Calyx commonly absent. (Orchard crab) . P. baccata XMalus. 

 Calyx persistent on the fruit. 11. 



11. Leaves rarely if at all lobei. ( (Apple) . P. Malus. 

 Leaves slightly crenately lobed. X P. Soulardi. 



12. Calyx persistent on the fruit. (American crab apples). 13. 

 Calyx absent from the fruit. Asiatic. P. Sieboldii. 



13. Leaves rather hastately lobed: twigs glabrate. P. ceronaria. 

 Leaves not hastate: twigs more woolly. 14. 



14. Flowers single. (Western crab). P. ioensis. 

 Flowers double. (Bechtel crab). P.- ioensis plena. 



ARONIA. Chokeberry. 



Deciduous shrubs with rather slender subterete branches 

 with roundish homogeneous pith; alternate appressed solitary 

 ovoid or oblong buds with about 3 exposed scales; rather 

 lanceolate moderate serrate leaves with slender black glands 

 on the midrib above; small low crescent-shaped leaf-scars with 

 3 bundle-traces; rather small cymose perfect polypetalous epi- 

 gynous flowers; and small red or black berry-like pomes. 



1. Leaves glabrate: fruit black. A. melanocarpa. 

 Leaves pubescent beneath. 2. 



2. Fruit black-purple. A. atropurpurea. 

 Fruit red. A. arbutifolia. 



SORBUS. Mountain Ash. Rowan Tree. 

 Deciduous small trees with rather soft pale or brown wood 

 with minute diffused ducts and fine medullary rays; moderate 

 or rather stout terete twigs; somewhat angled rather large 

 pith; alternate narrowly crescent-shaped of transverse some- 

 what raised leaf-scars with about 5 bundle-traces; no stipule- 

 scars; large appressed sessile buds with several scales; alter 

 nate odd-pinnate or simple petioled leaves with serrate blade 

 or leaflets; perfect small polypetalous epigynous white flowers 

 in compound terminal corymbs; and small red or orange berry- 

 like pomes. 



