Fig. 52. Diagrams showing evolutionary stages of change in position of sporangia 

 from sunken (a) to protuberant ( /, g, I, m ) and of stamen margins x x. A, a to g, 

 basic plan showing dehiscence: a, inlrorse; e, latrorse; /, extrorse; g, introrse. B, 

 variety of stages present in Magnolia and Liriodcndron: h, i, j. Magnolia maingayi, 

 M. nitida, M. grandiflora, respectively, introrse, sporangia slightly protuberant; 

 k, M. campbelli, latrorse, sporangia protuberant; I, Liriodendron, extrorse, sporan- 

 gia protuberant, change of position of outer smallest veins accompanying change 

 of sporangium position; m, Magnolia acuminata, latrorse-introrse, sporangia pro- 

 tuberant. ( h, i, adapted from Canright. ) 



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