The Origin of the Perianth in Seed-Plants. 
7i 
In Saururaceae and Piperaceae both bracteoles and perianth are 
absent. The flowers are simple and hermaphrodite or unisexual, 
presumably by abortion; the abortion of the stamens which also 
occurs to some extent in the hermaphrodite flowers (compare 
Houttuynin and Saururus) never results in the formation of a 
perianth. The bract which subtends the flower is more or less 
developed as a protective structure often encircling the base of the 
stamens and ovary, and this may be associated, as in Piper nigrum, 
with a concavity of the thick axis of the spike in which the flower is 
partially immersed. In Chloranthaceae also the flowers are 
hermaphrodite or unisexual. In Chloranthus the hermaphrodite 
flower stands in the axil of a bract, there are no lateral bracteoles, 
but a small scale structure (“ perianth’ ) arises at the base of the 
ovary in front of the bract; the flower is gynandrous. 
The single central stamen of the male flower of Casuarinci has a 
pair of bracteole-like perianth leaves which occupy the median 
position, alternating with the two lateral bracteoles ; the anterior 
perianth leaf may be absent. In the female the lateral bracteoles 
are present but no perianth leaves. 
In typically monochlamydeous flowers with a single whorl of 
stamens, such as occur in Ulmaceae, Moraceae or Urticaceae, the 
perianth leaves are opposite the stamens. This suggests rather a 
protective foliar outgrowth of the floral axis than a modification of 
a lower whorl of sporophylls. 
Turning to Monocotyledons we find in Nnjas the single axial 
stamen of the male flower, surrounded by a sac-like protective out- 
/ 
growth developed below it; we may call this a perianth. A second 
similar and lower outgrowth (the spathe) which is also sometimes 
present in the female flowers, may be compared with the bract or 
spathe which surrounds the cluster of female flowers in Zannichellia 
and is so frequently associated with the the flowers of submerged 
monocotyledons belonging to the Helobieae series. 
Other examples might be adduced which indicate that the origin 
of the perianth is not invariably to be sought in the modification of 
the members of the androecium. 
In many of the cases which we have quoted there is a strong 
indication of homology between bracteoles and perianth leaves. 
There is also a suggestion that the simple perianth originated from 
foliar outgrowths of the axis below the sporophylls, for the 
protection of the sporophylls. 
An order like Ranunculaceae, though with relatively simple 
