A 



A 



Fig. 128. Diagrams of primitive cotyledon types showing elongated "neck" and 

 stages in retention of tip within the seed coats. A to D, without blade, showing 

 stages in development of a suctorial tip: A, Alisma type; B, Allium type, tip not 

 withered, temporary retention of seed coat; C, Bowiea and Agave type, tip withered, 

 retention or not; D, Narcissus type, permanent retention. E to H, cotyledon with 

 blade; E, Paris type, no retention; F, Erythronium type, temporary retention; G, 

 Trillium and Costa type, temporary retention, tip strongly modified, collapsing after 

 freed from seed coat; H, Arum type, permanent retention of seed coat, blade greatly 

 reduced, permanent suctorial structure, a scutellum. {Adapted from Boyd and 



Schltckum,. "^ 



334 



