on 
312 MR. A. S. HORNE ON THE STRUCTURE AND 
5. DISCUSSION OF THE NATURE OF THE INFLORESCENCE AND FLOWER. 
The reduction of an inflorescence to its ultimate unit is shown by an evolutionary 
series. Some of the Cornels and Viburnums have their flowers arranged in cymose 
umbels. In Cornus sanguinea and Viburnum Lantana there is no definite arrange- 
ment in groups, but in Viburnum stellulatum the tendency of the flowers forming the 
umbel is to a triflorous arrangement with articulate pedicels. The expression of 
this tendency is complete in Aucuba japonica, where we have racemes of opposite 
and decussate cymose branches of the second order, a number of rudimentary flowers 
occurring about the point of articulation of the fertile ones. The Garryas have their 
female flowers in spikes of opposite and decussate, biparous, triflorous cymes or 
have the cymes reduced to single flowers. Among the Nyssas we have the limit 
of reduction. The polygamous inflorescence of the multiflora group consists of a short 
spike or capitulum of male and female flowers. In WN. sylvatica the iuflorescences 
are few-flowered and in a particular case consisted of hermaphrodite or female units 
borne in groups of three at about the same level on the torus. In NW. uniflora there 
is but a solitary flower. The Nyssas in this respect show some resemblance to the 
inflorescence of Davidia, which generally includes a single, obliquely situated, herma- 
phrodite flower. 
In iburnum stellulatum certain branches of the inflorescence may develop as 
one organ and bear at the top the small ultimate cymose branchlet. The individual 
vascular cylinders may remain distinct in the common ground-tissue, or may develop 
as one narrow, irregularly-shaped cylinder, so that the inflorescence is complete ( Pl. 38. 
figs. 15, 16). The floral organ or “double flower" of Prunus serrulata* is an 
inflorescence and presents in some ways a remarkable parallel to Davidia. There is 
generally a single, more or less obliquely-situated terminal bud, surrounded by a number 
of others which have grown together laterally with partial suppression of parts. The 
vascular structure of the common stalk (“peduncle”) consists of a number of small 
cylinders which originate from the single axial cylinder of the twig (Pl. 33. fig. 17). 
There is every reason to believe that a process of this kind has had its share in the 
inflorescence-building of Davidia, which has culminated in the production of a globular 
head of flowers accompanied by vascular complexity in the torus. 
The following considerations materially modify the original conception of the flower 
of Davidia :—(1) the total absence of a perianth; (2) the epigynous not hypogynous 
stamens; (3) more definite information with regard to the number and nature of the 
epigynousstamens. Baillon t believed the male flowers of the inflorescence to consist 
each of a single stamen ; Oliver +, on the other hand, considered them multistaminate, 
since the stamens are inserted in little foveoli on the torus and emerge in groups. In 
this connection the following evidence is available :—(1) the stamens emerge in groups 
* The Double Chinese Cherry, introduced from China in 1829. It blooms in April and has white or rose- -tinted 
flowers. 
T Baillon in * Adansonia,’ x. (1871) p. 114. t D. Oliver in Hooker, Ic. Pl. t. 1961. 
