110 MISSOURI BOTANICAL GARDEN BULLETIN 
diseased, interfering, or misshapen growths should be re- 
moved. Occasionally the dictates of formal gardening re- 
uire shaping into artificial forms, but ordinarily such 
shearing results in mutilation and disfigurement. Trimming 
of shrubs is justified when increased vigor is sought, this 
being accomplished by gradual thinning of the old wood 
and, in exceptional cases, cutting back to the ground plants 
that lose their winter attractiveness as the stems grow old 
(Cornus, Kerria, etc.). Before any pruning of shrubs is 
attempted it is essential to recognize their flowering habits. 
The spring and early summer-blooming kinds produce 
flowers upon wood which is formed during the previous 
year, thus necessitating pruning shortly after the flowering 
season so that the new growths may steko buds for the 
next season. ‘The late summer and fall-blooming plants 
produce flowers on the same season’s wood and require 
Shen in the fall. In either case, the work should be 
one after flowering. 
The following table indicates the more common shrubs 
and the Spe to which they belong. Those marked with 
8 
an asterisk are profited by annual pruning. 
SPRING AND SUMMER- LATE SUMMER AND FALL- 
FLOWERING FLOWERING 
Benzoin aestivale *Amorpha fruticosa 
Berberis Thunbergii *Buddleia Davidii (cut back in 
Cercis canadensis spring to prevent danger of rot- 
Chionanthus virginica ting) 
Cornus (numerous species) Ceanothus americanus 
Cotoneaster (numerous species) Cephalanthus occidentalis 
*Deutzia (numerous species) *Clethra alnifolia 
*Diervilla hybrida Hamamelis virginiana 
Dirca palustris Hibiscus syriacus 
Elaeagnus angustifolia *Hydrangea arborescens 
Euonymus (several species) *Hydrangea paniculata 
Forsythia (several species) *Sambucus canadensis 
Hippophae rhamnoides *Sorbaria arborea 
*Kerria japonica Spiraea Billiardii 
Ligustrum (several species) Spiraea Douglasii 
Lonicera (several species) Spiraea tomentosa 
Philadelphus (several species) Symphoricarpos racemosus 
Physocarpus opulifolius *Vitex incisa 
Rhamnus cathartica 
Rhodotypos kerrioides 
Robinia hispida 
Spiraea prunifolia 
*Spiraea Thunbergii 
Spiraea Van Houttei 
*Stephanandra flexuosa 
Syringa (numerous species) 
Viburnum (numerous species) 
The matter of pruning hedges is of vital importance. 
The prime requisite of a hedge is a thick bottom, which is 
