20 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE 
MorRPHOLOGY OF WHOLE Insect FLOWERS 
The flowers usually employed in the production of insect powder 
or Pyrethrum powder are derived from either the Dalmatian or the 
Persian insect flowers, botanically known as Chrysanthemum cine- 
rarvefolium (Trey.) Bocce. and C. rosewum Web. & Mohr., respectively. 
The Dalmatian flowers compose the greater part of the commercial 
insect powders, the Persian flowers being rarely seen in commerce at 
the present time. Of recent years, Japanese insect flowers have 
been coming into the market. According to one authority (24) the 
form known as C. vndicum, with a yellow ray flower, is widely spread 
through China and Japan, while in the mountains of Hupeh occurs 
a white or pink rayed form, which has been named (©. morifolium. 
Doctor Henry, who has collected specimens which are in the Kew 
herbarium, considered these two wild panes the probable progenitors 
of the cultivated strains. As far as histological characters are con- 
cerned, the Japanese flowers can not be distinguished from (©. cine- 
rarvefolrum. 
Siedler’s (150, 258) morphological description of the Dalmatian 
flowers may be summarized as follows: 
The Dalmatian flower stem is 8-sided and very hairy; receptacle slightly 
arched; involucre consisting of 3 rows of scales, the inner scales lanceolate 
and about 4 mm. long, the scales of the middle row about 6 mm. long. All of 
the scales have a flat inner surface, the outer surface being more or less keeled, 
possessing a scarious margin and covered with hairs. The whitish ray flowers 
measure about 15 mm. in length and 4 mm. in width, 3-toothed at the tip, the 
middle tooth being somewhat smaller than the other two. The disk flowers 
are tube-shaped and 5-toothed, possessing the typical Composite oil glands and 
containing more or less of the yellow, 3-pored, spiny pollen grains. The fruits 
of the ray flowers exhibit a different structure from those of the disk flowers, 
being somewhat flattened on the side iying next to the outer bracts, and pos- 
sessing two furrows, while the inner side has three. The fruits of the disk 
florets consist of 4, sometimes 6, nerves. A small crown is present on all the 
fruits. 
Collin (47) designated three distinct commercial varieties of 
Dalmatian insect flowers: 
1. Closed flowers.—F lower heads, varying from 3 to 7 mm. in diameter, gen- 
erally furnished with a very short striated peduncle. Bracts, greenish-yellow, 
closely appressed. Corollas of ligulate florets almost always entire; grayish- 
white in color, and wrinkled and shriveled over the tubular florets, so as to 
conceal them almost completely. Very few expanded flowers present; very few 
fragments of corollas, ovaries, or bracts mixed with flower heads. 
2. Half-closed flowers——Peduncle longer, even 4 or 5 cm. long. Flower heads 
full, bracts of a yellowish-gray color. Ligulate florets can usually be dis- 
tinguished; tubular florets still retain their corollas more or less intact. 
3. Open flowers.—Recognized by the size of the flower heads, many of which 
attain a diameter of from 9 to il mm. Usually completely expanded when 
gathered and hence few of them intact; some ligulate florets destitute of corollas 
and in many others the corollas of the tubular florets have been separated from 
the ovaries which remain attached to the receptacle. This variety contains 
abundant débris of the corollas and ovaries, and therefore is not as choice com- 
mercially as classes 1 and 2. The various parts of the Dalmatian flower head 
are as follows: Bracts, outermost thicker and shorter than the others; more 
strongly curved and more pointed at the apex; those from the middle row 
lanceolate, slightly curved; the inner scales are as long as the middle ones_but 
thinner and spatulate in shape. All scales thickened in the center, gradually 
becoming thinner toward the margin, which is scarious and transparent. Ligulate 
florets with three teeth at the apex, central tooth smaller than the other two. 
Calyx with fringed or slashed margin. Ovary possesses five projecting ridges. 
Tubular floret corolla rather deeply 5-toothed. Peduncle channeled and hairy. 
