The fruit of celery (Plate 121), like other umbelliferous fruits, is composed of the pericarp and the seed.
The pericarp is composed of epicarp cells, mesocarp cells, endocarp cells, and in each rib a vascular bundle. The seed is composed of the spermoderm, endosperm, and embryo. Each of these parts has a characteristic structure.
Epicarp. The cells of the epicarp (Fig. 1) are papillæ and the outer wall is striated. The papillæ do not show, however, unless the cell is cut across the centre, which is the point at which the papillæ are located.
PLATE 121
Cross-Section of Celery Fruit (Apium graveolens, L.)
1. Epicarp. 2. Mesocarp. 3. Vascular bundle. 4. Endocarp. 5. Spermoderm. 6. Endosperm. 7. Secretion cavity.
PLATE 122
Diagrammatic Drawing of the
1. Cross-section of wild celery seed (Apium graveolens, L.).
2. Cross-section of cultivated celery seed (Apium graveolens, L.).
Mesocarp. In the rib part of the mesocarp (Fig. 2) is a vascular bundle, and between the ribs one or more secretion cavities. The vascular bundles are small and are surrounded by irregular-shaped mesocarp cells.