ON THE VASCULAR SYSTEMS OF FLORAL ORGANS. 151 
On the Vascular Systems of Floral Organs, and their Importance 
in the Interpretation of the Morphology of Flowers. By 
Rev. Prof. G. Hengfow, M.A., F.L.S., &c. 
[Read 7th March, 1889.] 
(Prates XXIII.-XXXII.) 
INTRODUCTION. 
Tur study of the morphology of flowers is tolerably comp lete 
as it forms the basis of Systematic Botany. To understand their 
structure, however, when it is obscure in the fully developed 
state, as is not infrequently the case, the development of the 
floral organs must be traced. Payer’s ‘ Organogénie Végétale 
comparée, without being an absolutely exhaustive treatise, 
nevertheless goes far towards supplying very nearly all that is 
needed in this direction. The third and final investigation, how- 
ever, seems yet to be done—namely, a research into the origin 
and distribution of the vaseular eords within the floral axis, with 
the view of discovering how the various members of the floral 
whorls are supplied with them. 
The importance of this line of research lies in the fact that the 
origin, position, and union, when it occurs, of every organ are bound 
to the particular cord or “trace” in the axis which subsequently 
enters it. No visibly appreciable differences are to be detected 
between the traces of a sepal, a petal, a stamen, or a carpel. 
They may, or may not, vary somewhat in size, but nothing of the 
nature of differential characters can be relied upon. They all 
consist of the same two elements—spiral vessels or tracheæ, 
ng xylem, and sieve-tubes or soft bast, eonstituting 
representi 
A difference in the amount of these two elements, 
the phloém. 
and especially in their arrangement in the cord, supplies some 
features of importance—more particularly one which Ph. van 
Tieghem recognized but applied somewhat too rigorously, as it 
scems to me. In his investigations upon the anatomy of the 
pistil*, which were specially directed to ascertain how far the axis 
entered into the structure of that organ, he regarded a circle of 
* ‘Recherches sur la Structure du Pistil, 1868. To the later edition of which 
he added ‘ L’ Anatomie Comparée de la Fleur, 1871. See also “ Structure et Déve- 
loppement du Fruit,” par M. C. Cave, Ann. des Sei. Nat. 5° ser. x. p. 123. 
LINN. JOURN.—BOTANY, VOL. XXVIIT. N 
