432 BOTANICAL GAZETTE ’ | DECEMBER 
indeterminate inflorescence the lower or outer buds normally bloom 
first, because the terminal bud continues vegetative while the axillary 
buds are forming floral organs. As the order of anthesis and that of 
development are the same, whatever affects the order of development 
will in like manner affect the order of 
flowering. Thus, if for any cause the 
terminal bud of a normally indetermin- 
ate inflorescence develops floral organs 
before the last lateral buds have attained 
a like state of development, a mixed 
inflorescence results, as has been occas- 
ionally seen in Digitalis. 
A very interesting case of variation from the normal order of devel- 
opment is seen in the genus Dipsacus, where the dense crowding of 
the flowers in the head forces the lower buds down against the invo- 
lucre and so retards their development. The next circle of buds is 
not crowded so much, and the development is proportionately less 
retarded. The pressure becomes less and less as the buds occupy 4 
higher and higher position in the head, until at about the middle a 
point is reached where the bud pressure isso much reduced that from that 
point to the apex of the head a normal order of development obtains, 
showing Dipsacus to have a normally indeterminate inflorescence. In 
flowering the center of the head blooms first, and thence one flower 
zone proceeds upward according to the normal order of development, 
and another downward according to the order of development brought 
about by bud pressure. 
Fic. 4. Verticillate inflores- 
cence of Mentha Canadensis. 
SUMMARY. 
- Most cases of branch and flower arrangement may be explained 
by a law that a bud, real or potential, occurs in the axil of every leaf. 
and terminates every axis. 
2. Ifa bud is removed from the axil of a leaf by adnation or by 
development into a branch, a secondary axillary bud may form in the 
axil of the leaf, and if that too is removed a tertiary axillary bud may 
form, etc. 
3- Bud pressures explain reduction of bracts and their failure to 
appear, as well as many modifications in the normal order of anthesis. 
— Geo. H. Suutt, Yellow Springs, Ohio. 
si EP ane ee A —" 
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