APIUM GRAVEOLENS 



457 



of the abundant endosperm, which completely surrounds the small 

 embryo, are thick-walled and contain fat and aleurone grains. 

 (Fig. i3X, D.) No starch is present and Kondo reports the absence 

 of crystals of calcium oxalate which are frequently found in the 

 endosperm of some umbelliferous seeds. The embryo is straight 

 and lies in the endosperm with the tip of the minute primary root 

 inclined upward. 



Development of the Seedling. — The germination and growth 

 of the seedling are relatively slow. In commercial practice, the 

 seed is either sown in outdoor seed beds, which is the custom in the 



Fig. 2.33. Stages in development of celery seedling. 



South; or grown in hotbeds or cold frames, as is the common 

 method in the North. 



The primary tap root develops laterals which are arranged in two 

 double rows; and, following the emergence of the narrowly ovate 

 cotyledons, the first two foliage leaves expand. The petioles are 

 slender, and the simple, three-lobed blades have serrate to dentate 

 margins. (Fig. 2.33.) When the crown of the plant has reached 

 a diameter of 3^ to ^ of an inch, it is transplanted. 



Anatomy of the Root. — The slender primary root has a diarch 

 protostele, and resembles the primary root of parsnip, as described 

 by Warning (18), in the principal details of its structure. Its 

 ontogeny follows Janczewski's (10) third type in which there is a 

 definite plerome and periblem, and a combined calyptrogen-dermat- 



