142 BOTANICAL GAZETTE [FEBRUARY 
itself has hardly had an opportunity to proceed at all, nor have the 
clasping leaves developed to any extent, when in their axils an 
active meristem begins to give rise to the initials of another floral 
head. By this time the outermost cycle of bracts forming the 
involucre has fairly grown beyond the floral head, which they 
encircle, and the entire capitulum becomes one mass of protuber- 
ances, the initials of the bracts, which later subtend individual 
flowers. 
Flowers 
The flowers of D. sylvestris are arranged in the capitulum in the 
form of a low spiral, and so appear to be set in diagonal rows (figs. 
3-14). The method of blossoming is unique. Ordinarily one would 
expect the blossoming to begin at the base and extend toward the tip, 
but the blossom tide begins at the middle and extends both ways (2). 
The flower itself consists of a white tube, which is divided at its 
end into four purple lobes. Of these four lobes the lowest is a 
trifle longer than the others and turns up slightly at its tip. Alter- 
nating with the lobes are four stamens, inserted on the tube of the 
corolla. A much reduced calyx, which encircles the base of the 
corolla, adheres to the inferior ovary. This typical epigynous 
flower is further characterized by a four-leaved calyx-like involucel, 
which invests the ovary and fruit (fig. 14.) The individual 
flowers begin their development as axial outgrowths of the bracts 
besetting the capitulum. This undifferentiated mass of cells, 
somewhat rounded at first, soon broadens a little, and the distinct 
lobes of the corolla appear on the peripheral portion (fig. 10). 
Next in appearance are the primordia of the stamens, which form 
the succeeding inner cycle (fig. 11). Soon after this the tissue 
below the lobes of the corolla and stamen initials begins to elongate 
en masse, forming a tubular ring. Following so soon that it would 
almost seem to be simultaneous, is the appearance of a twofold lateral 
swelling just below the base of the corolla (fig. 11). The upper 
protuberances are the primordia of the calyx and the lower develop 
into a calyx-like involucel, which later invests the ovary and fruit 
(figs. 11, 14). The last to make their appearance are the carpel 
lobes, which appear as basal outgrowths from the inner surface 
of the tubular cavity (fig. 12). 
