232 



BOTANY OF CROP PLANTS 



Roots. — The root system is fibrous and very shallow (Fig. 

 88). The roots arise from the reduced stem, forming a 

 fibrous tuft. 



Stems. — With but few exceptions, species of the genus 

 Allium bear bulbs. In chives {Allium schmnoprasum), the 

 bulbs are very small (Fig. 88), and in Welsh onion (Allium 

 fistulosum) and leek (Allium porrum), they are nearly always 



Fig. 89. — Leek (Allium porrum). 



absent (Figs. 88 and 89) . In the common onion (Allium cepa) , 

 they are large and well developed. Examination of the 

 mature bulb of the common onion shows it to be made up of 

 the much thickened bases of leaves, attached to a compara- 

 tively small, conical stem (Fig. 14). This is best seen in a 

 median, longitudinal section. From a terminal bud on this 

 small, underground stem, there is sent up a long hollow or 

 solid, leafless stem (Fig. 90) (scape) bearing an inflorescence 

 at the top, which in this case is an umbel. Lateral buds are 



