28 
BULLETIN OF THE LABORATORIES 
posed buds are occasionally found among herbaceous plants, in the far 
greater number of cases they are inserted at about the same level and 
superposition can only be morphologically asserted from the evident 
origin and development of the buds. Ligneous and herbaceous 
plants are almost directly opposed to one another as to the character of 
their superposition. 
Again, while in ligneous plants the superposed buds are usually 
found during their first season as buds, in herbaceous plants one or 
more buds are immediately developed into branches. Since the aerial 
portion of herbs in our climate is destined to decay at the approach of 
autumn, and sometimes even before that season arrives, buds do not 
long remain in a rudimentary and inactive state, but grow rapidly and 
form branches and flowers. The first formed bud in an herb is there- 
fore unusually a well developed branch before the second bud in the 
same axil becomes visible to any but the careful observer. In some 
plants at this period the petiole of the subtending leaf must be care- 
fully removed and the lower part of the developed branch closely ex- 
amined in order to find the flattened bud lying closely against it. 
Some of the small buds later in the season turn into branches and even 
bear flowers, but most of them will never develop unless some accident 
should befall the branch already formed. 
Whenever the phyllotaxy of the branch bearing superposed buds is 
that of decussating pairs of leaves, the lowest pair of bracts or leaves 
of each axillary member is always placed transversely to the stem and 
its subtending leaf. The lowest pair of leaves or bracts are there- 
fore similarly inserted in all members found in the same axil. In 
members which belong to plants having a spiral arrangement of 
leaves, the lowest bract or leaf in all specimens examined was placed 
towards the left or right of the subtending leaf, i. e. transversely, but 
not always on the same side. Members of the same axil may have 
an insertion which places the first bract or leaf always on the same 
side of the stem, or they may be regularly opposed to one another, or 
there may be no definite arrangement whatever in this respect. The 
same thing may be said about corresponding members of different 
axils. 
A form of superposition occurs in some herbaceous plants which 
seems to occupy a middle ground between superposed and collateral 
buds. In Thalictrum dioicum, for instance, the oldest bud or branch 
is nearly in the axil of the subtending leaf, then by means of inverted 
