MIDSEASON FLOWERING TREES AND SHRUBS 49 



well worth growing. A sixth species (5. Lindleyand) 

 from the Himalayas is not hardy with us. 



Three species of Adam's Needle (Yucca flaccida, 

 native of the southern Appalachians, Y. filamentosa 

 from Stone Mountain, Georgia, and Y. glauca, native 

 of the eastern slopes of the Rocky Mountains) are 

 hardy in the Arnold Arboretum. With their spear- 

 like leaves these plants are interesting at all seasons 

 and when in flower there are few if any subjects more 

 beautiful. The tall, branching inflorescence and nod- 

 ding white flowers, in the daytime more or less 

 top-shaped, expand on moonlight nights when they 

 attract the moths which effect the fertilization of the 

 flowers. 



Of shrubs with yellow flowers there are several, 

 all native of southern Europe, the Caucasus, and Asia 

 Minor, which blossom in July. Most interesting 

 among these are Cytisus nigricans, C. capitatus, and 

 Genista tinctoria, van data, all three good garden 

 plants unfortunately too rarely seen in American 

 gardens. The Bladder Sennas (Colutea arborescens 

 and C. cilicicd) flower in July, and C. orientalis, which 

 flowers earlier is covered with large, thin-walled in- 

 flated pods which are tinged with pink and are very 

 ornamental. 



The yellow shrubby Cinquefoil (Potentilla fruti- 



