454 THE STRUCTURE OF ECONOMIC PLANTS 



grow out from the base of the plant. Thompson (x4) states that 

 the major portion of the roots occupies the upper 6 inches of soil, 

 many of them being within i or 3 inches of the surface while a few 

 penetrate to a depth of 2. feet or more. 



The Shoot. — The subconical, fleshy stem remains short during 

 the first year and bears a spiral rosette of leaves. The broadened 



bases of their petioles over- 

 lap one another and these, 

 with a variable portion of 

 the fleshy stem, constitute 

 the edible portion of the 

 plant. The number of 

 leaves is not constant, but 

 commonly there are xo to 

 15 in the rosette, including 

 the small, immature, cen- 

 trally located ones. The 

 outer 11. or 15 leaves are 

 large, with somewhat erect 

 petioles that range from 4 

 to 10 inches in length. The 

 petiole is glabrous, crescen- 

 tic in transection with a 

 prominently ribbed abaxial 

 surface, and a relatively 

 smooth concave adaxial 

 one. The blade is odd-pinnately compound, and usually there are 

 two or three pairs of stalked leaflets. These are pinnately lobed 

 or compounded, and the ultimate divisions are broadly wedge- 

 shaped with coarsely dentate or crenate margins. 



The Inflorescence and Flower. — The flowers are borne in 

 compound umbels which may or may not be subtended by an in- 

 volucre, and involucels may or may not subtend the umbellets. 

 The flowers are perfect and epigynous, with calyx lobes that are 

 rudimentary or lacking. The small white or greenish-white petals 

 are incurved at their tips. Alternate with them are five stamens 

 with very slender filaments and versatile anthers which are diverged 

 at a level above the top of the ovary. The pistil consists of two 

 carpels which cohere during early development to form a two- 

 loculed ovary terminated by two distinct styles. (Fig. 2.31.) The 



Fig. 131. A, habit of inflorescence ; B, lateral view 

 of flower ; C, face view of same; D, fruit. 



