The papillæ of the stigma of the ray (Plate 117, Fig. 3) and disk flowers (Plate 117, Fig. 5) of matricaria are similar in structure, but the papillæ of the disk flowers are larger.
The papillæ of the stigma of the ligulate flowers of insect flowers (Plate 117, Fig. 5) are tubular; the walls are striated, and in each papilla there is a small yellow globule, while the papillæ of the disk flowers (Plate 115, Fig. 2) are long and tubular, and the walls are thick.
The papillæ of the stigma of the ray flowers of arnica (Plate 115, Fig. 1) are very short and tubular. The walls are thin and the cell contents appear as small, bright-yellow globules, while the papillæ of the stigma of the disk flowers (Plate 116, Fig. 3) are broadest at the base, the apex is pointed, and the yellow globules are larger.
The solitary hairs are divided into the branched and non-branched hairs.
POWDERED INSECT FLOWERS
The microscopic examination of insect powder is difficult for the reason that there are so many elements to be constantly kept in mind. The parts of the flower which contribute characteristic cells are the stem, involucre, ray flowers, disk flowers, and the receptacle. In each of these parts there are many different types of cells.
There are practically two types of flowers found in insect powder of commerce: first, closed or immature flowers, and secondly, open or mature flowers. As explained above, the half-open flowers consist largely of the two above-named varieties. Let us first consider the structure of the closed insect flowers as illustrated in Plate 118.
PLATE 118
Powdered Closed Insect Flower
(Chrysanthemum cinerariifolium, [Trev.] Vis.)
1. Edge of scale. 2. Fibre of scale. 3. Hairs. 4. Upper epidermis of ray flower. 5. Under epidermis of ray flower. 6. Cross-section of ray petal. 7. Parenchyma of ray flowers with crystals. 8. Lobe of disk petal. 9. Filament tissue. 10. Calyx tissue, 11. Lobe of stamen. 12. Pollen. 13. Papillæ of stigma. 14. Secretion cavity with surrounding cells. 15. Parenchyma of the receptacle.