ROSACEAE. 91 
PHYSOCARPUS. 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. lLeaf-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, 
gE bs 
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. 
