THE SEED 



371 



cells. In Tjca, only a few remnants of the integument persist in the 

 fruit. Seed coats consisting of a single layer of cells are frequent in 

 highly specialized seeds (Fig. 138B) — those of the orcliids, some epi- 

 phytes and parasites {Orobanche, Monotropa). 



Fig. 137. Longitudinal sections of A, a dicotyledonous seed. Beta vulgaris; and B, 

 a monocotyledonous fruit, Sorghum sp. (sugar cane), a, aleurone layer of endo- 

 sperm; c, coleoptile; ch, chalaza; cr, coleorhiza; e, endosperm; eb, embryo; /, funi- 

 cle; h, hilum; i, inner integument; /, plumular leaf; n, nucellar perisperm; p, peri- 

 sperm; pc, pericarp; r, root primordium; re, root cap; s, scutellum; se, seed coats; 

 st, base of style. (A, after Artsehwager; B, after Artschwager, Brandcs, and 

 Starrett. ) 



Major and minor appendages may develop on the integuments — 

 wings, spines, hairs, glands; these may be epidermal in origin or involve 

 deeper tissues also. Type of appendages may be of some importance in 

 indicating relationships. In the Meliaceae, the fleshy seeds of Amoora 

 have winglike appendages, suggesting derivation from winged genera in 

 the family. Appendages of the chalazal region are unusual, and their 

 presence may suggest relationships. 



