526 MR, J. PARKIN ON THE 
growth of the plumular shoot is arrested before the flowering stage is 
attained. The first flower will then terminate a subordinate shoot, though it 
may appear as if it crowned the main primary stem on account of the 
formation of a sympodium. 
In herbaceous perennials of temperate climates (with solitary terminal 
flowers) which do not bloom during the first season of the plant’s activity, the 
earliest flower produced cannot terminate the plumular axis, for this will have 
died down completely at the end of the first season ; it must therefore be 
borne by a subordinate shoot. 
The earliest mode of flowering would seem, then, to be that in which the 
first flower produced terminated the primary (plumular) axis of the plant, 
and later flowers appeared at the ends of subordinate leafy axes. Among 
annuals, cases are not uncommon now. Unmistakable flowers terminal to the 
plumular axis have come to my notice in species of Nigella and of Papaver ; 
also in Adonis autumnalis, Saponaria calabrica, and Silene pendula. By 
further observation there is little doubt but that the list could be greatly 
extended. Shrubs, trees, and herbaceous perennials with solitary terminal 
flowers require close watching from the seedling stage onwards to see if the 
primary axis, barring accidental damage, eventually ends in a flower. 
Tropical plants would serve better for this study, as the growing tips of 
the shoots are not subjected to winter frosts. 
Turning now to solitary terminal flowers in the wider sense, instances are 
numerous, and particularly so in those families which are now generally 
recognised as containing a large number of primitive features in their floral 
parts, e. g., Magnoliacez, Calycanthacew, Ranuneulacem, Papaveraces, and 
Rosaceæ. These families are not only interesting in affording examples of 
forms with solitary terminal flowers, but also in revealing how the simplest 
flower-cluster—the dichasium—arises from the single apically-borne flower. 
It will be expedient, then, to treat of the origin of the simple dichasium, 
along with the detailed study of some of the genera containing examples of 
the solitary terminal flower. 
MAGNOLIACES. 
Magnolia.—This interesting genus is especially characterised by its large 
solitary terminal flowers. As regards the number of foliage leaves on the 
flower-bearing shoot, the species examined by the author permit themselves 
to be arranged roughly into three groups :— 
(1) Several foliage leaves on the flowering shoot. The flower expands 
after the foliage is mature. Evergreen and summer-flowering 
species. M. grandiflora and probably M. Delavayi, judging from 
figures and descriptions. 
