SPERMATOPHYTES—ANGIOSPERMS 
297 
in diameter will give a very complete series of stages in the 
development of the floral organs. Preparations from the apex 
of the shoot taken after the inflorescence appears above ground are 
not to be compared with those taken early in the season, because 
the pedicels begin to diverge so early that median longitudinal 
sections of the flowers are comparatively rare. Fix in chromo-acetic 
acid and stain in Delafield’s haematoxylin. The sections should be 
longitudinal and about 5 p thick. Capsella shows the hypogynous 
type of development. The order of appearance of floral parts is 
(1) calyx, (2) stamens, (3) carpels, and (4) petals. The ovary is 
compound (syncarpous). 
Ranunculus, which is also hypogynous, will illustrate the develop¬ 
ment of the simple (apocarpous) ovary. The ovules appear quite 
early, so that the archesporial cell, or even the megaspores, may be 
seen while the carpel is still as open as in any gymnosperm. The 
whole structure is a simple strobilus. 
Rumex crispus (Yellow Dock) is also a good hypogynous type, and 
the densely clustered flowers afford a fine series of stages. Besides, 
in transverse sections, the early stages in spermatogenesis are very 
clear. 
In the willows, Salix , the bud scales must be removed and the 
copious hairs should be trimmed off as much as possible with scissors, 
after which the catkin should be slabbed a little on opposite sides 
to facilitate penetration. This is a fine illustration of a compound 
strobilus. 
The cat-tail, Typha, presents a simple type of floral development. 
The leaves should be dissected away long before the flowers can be 
seen from the outside. The cylindrical clusters, varying in diameter 
from 2 or 3 mm. up to the size of one’s finger, will afford a complete 
series of stages. Until the spadix reaches the diameter of a lead 
pencil, transverse sections are easily cut. For later stages, the outer 
part of the spadix should be sliced off so that only enough spadix is 
retained to hold the florets in place. 
Prunus and many other members of the Rosaceae furnish examples 
of the perigynous type of development. In many of them the floral 
parts do not occur in the usual succession. 
The epigynous type is well shown in the Compositae. The order 
of appearance is (1) corolla, (2) stamens, (3) carpels, and (4) calyx 
(pappus). 
