ROSACEAE. 



91 



Physogabpus. Ninebark. 

 (Family Rosaceae). 



Loosely branching shrubs with 

 quickly shredding brown bark: 

 deciduous. Twigs terete but 5- 

 lined from the nodes, moderately 

 slender, somewhat zig-zag: pith 

 relatively large, brownish, round, 

 homogeneous. Buds rather small, 

 solitary, sessile, conical-oblong or 

 ovoid, with about 5 rather loose 

 brown scales. Leaf-scars alter- 

 nate, half-elliptical or somewhat 

 3-lobed, raised on a distinct 

 cushion bearing the small stipule- 

 scars: bundle-traces 5, unequal, 

 the lower one distinctly larger. 

 Fruit, as clustered small follicles, 

 may be present in winter. Some- 

 times united with Spiraea or re- 

 ferred to Neillia or Opulaster. 



Winter character references: 

 P. amurensis. Schneider, f. 152. 

 P. opulifolius. Bosemann, 76; Schneider, f. 152; Willkomm, 

 11. 



Novices frequently have difficulty in distinguishing be- 

 tween ninebark and the common snowball (Viburnum Opu- 

 lus). Fundamental distinctions lie in its alternate leaves or 

 short broad leaf-scars, and in its sessile buds with several 

 scales; the Viburnum having narrow opposite leaf-scars and 

 stalked plump buds with a closed outer sac. 



1. Puberulent: buds ovoid, spreading. P. amurensis. 

 Twigs glabrous: buds pointed, appressed. 2. 



2. Follicles puberulent. P. intermedius. 

 Follicles glabrous. (1). P. opulifolius. 



