Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Sterile-Fertile Leaf Dimorphy and Evolution of Soral Types in Polybotrya (Dryopteridaceae)

Robbin C. Moran
Systematic Botany
Vol. 12, No. 4 (Oct. - Dec., 1987), pp. 617-628
DOI: 10.2307/2418896
Stable URL: http://www.jstor.org/stable/2418896
Page Count: 12
  • Read Online (Free)
  • Download ($12.00)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Sterile-Fertile Leaf Dimorphy and Evolution of Soral Types in Polybotrya (Dryopteridaceae)
Preview not available

Abstract

The neotropical fern genus Polybotrya has strongly dimorphic sterile and fertile leaves (trophophylls and sporophylls). Sterile-fertile leaf dimorphy involves an ensemble of characteristics and not merely a single feature of the leaf. The reduction of green tissue is the most conspicuous aspect of dimorphy, but differences also occur in seasonality, duration, orientation, placement, size, color, texture, and venation. The sori of Polybotrya were previously described as acrostichoid, but three types of sori occur in the genus: botryoid, coenosoric, and a new type here termed "amphiacrostichoid." Botryoid sori, which are round and discrete, are considered primitive on the basis of outgroup comparison with other dryopteroid ferns. Coenosoric sori, which are oblong to linear, probably evolved from the botryoid type by basipetal fusion of the sori. Amphiacrostichoid sori developed from a coenosoric ancestor by the expansion of the margins of the receptacle beyond the original adaxial surface. As a result, the receptacle assumed its own adaxial surface and sporangia appeared on both surfaces of the leaf. Coenosoric and amphiacrostichoid sori contain diplodesmic veins that develop from the normal veins of the sterile leaf.

Page Thumbnails

  • Thumbnail: Page 
617
    617
  • Thumbnail: Page 
618
    618
  • Thumbnail: Page 
619
    619
  • Thumbnail: Page 
620
    620
  • Thumbnail: Page 
621
    621
  • Thumbnail: Page 
622
    622
  • Thumbnail: Page 
623
    623
  • Thumbnail: Page 
624
    624
  • Thumbnail: Page 
625
    625
  • Thumbnail: Page 
626
    626
  • Thumbnail: Page 
627
    627
  • Thumbnail: Page 
628
    628