Parnassia and its bearing on the A Affinities of the Genus. 493 
three arcs fuse and branch in such a way as to form a five-pointed hollow 
star (Text-fig. 1, B). Each of the three arcs is responsible for one entire arm 
of the star — two of them each give rise, in addition, to half an arm-— while 
the third produces two half-arms which fuse with those derived from the 
neighbouring arcs. Each arm of the star gives rise to two bundles, lying 
on the same radius of the axis (Text-fig. 1, c). The inner strand is destined 
for a stamen, while the outer, which branches into three as it nears the surface, 
will supply a sepal (Text-fig. 3, H). Another set of five bundles is given 
off from between the arms of the star. Each of these bundles, at a slightly 
higher level, also divides into two strands on the same radius, of which 
the outer enters a petal and the inner a nectary. In Text-fig. 3, G, the 
separation of petal and staminode (nectary) bundles is seen occurring in the 
Text-fig. i. Diagrams to show the origin of the vascular bundles of the androecium in 
Parnassia palustris , L. a. Transverse section of the vascular system in the pedicel below the 
flower. The three arcs of vascular tissue are shaded differently, so that the part which they play 
may be followed in the succeeding diagrams. B. Transverse section of the vascular system at the 
extreme base of the flower, showing the three arcs uniting and branching to supply the strands for 
the different whorls, c. Transverse section of the vascular system at a slightly higher level than B. 
( sep.b . — sepal bundle ; st.b. — stamen bundle ; pet.b. + std.b. = the bundle which, at a slightly higher 
level, will divide into a petal bundle externally and a staminode bundle internally.) In B and c 
the strands which supply the gynaeceum are omitted. 
case of the N. and N.E. petals. The remaining three petals have already 
become entirely detached from the axis, and their vascular system has 
undergone its primary division into three, followed, in the case of the S.W. 
petal, by further branching. 
It will be noticed that the stamen bundles become free from the sepal 
bundles at a level below that at which the staminode bundles separate from 
the petal bundles. We are thus able to confirm, on anatomical grounds, 
the conclusion reached by Drude from a study of the development of the 
flower — namely, that the staminodes (or nectaries) are to be regarded as 
representing the internal whorl of the androecium, although, in the mature 
flower, there is no outward indication of this fact. 
In Text-fig. 1 the strands which supply the carpels are not represented, 
since it is only the androecium with which we are particularly concerned. 
