The Development of the Flower of the Dipsacaceae . 1 
BY 
Z. SZABO, 
Budapest, Hungary. 
With Plates VII and VIII and five Figures in the Text. 
I ''HE development of the flower of the Dipsacaceae, according to the 
publications of Buchenau (1), Payer (6), van Tieghem (8), and my own 
former investigations (7), seems to be clear. There are, however, several 
questions not yet solved. Some more exact microtechnical work and the 
precise observation of the development are required to answer them. 
These unsolved questions are as follows : i. How does the carpel appear 
during the successive development of the different parts of the flower, and 
how is it a participant in the formation of the ovary ? 2. Is the wall of the 
ovary an axile or a carpellary formation ? 3. What is the arrangement of 
the vascular tissues of the flower-parts ? 
I wish to answer these questions, discussing the successive development 
of the flower-parts and the arrangement of their vascular bundles after having 
given a general description of the flower? 
I. The Flower. 
According to van Tieghem’s precise definition, the flower of the 
Dipsacaceae is nothing but a single-flowered capitulum, which appears in the 
axil of a bract closely surrounded with an involucel. The stalk of this 
partial capitulum usually fails to develop appreciably ; it elongates only in 
cases of proliferation. The involucel originates in four joined bracts, as is 
a general rule in the family of the Dipsacaceae. These four bracts, in 
prolific examples, may also form separate diverging involucels; even the 
number of the bracts may increase, as has been observed in several irregular 
cases. The situation of the four leaves of a normal involucel is median 
transverse, and it surrounds the inferior ovary, resembling a closed tube. 
After fertilization it grows longer, enclosing the genuine fruit, and as it is 
a closed integument, it falls off together with the fruit. The flower itself is 
hermaphrodite; its single leaf-zones are situated at the top of the inferior 
[Annals of Botany, Vol. XXXVII. No. CXLVI. April, 1923.] 
1 From the session of Feb. 17, 1922, of the Academie St. Stephen, Budapest, Hungary. 
