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.

Calamocarpon Insignis, a New Genus of Heterosporous, Petrified Calamitean Cones from the American Carboniferous

Robert W. Baxter
American Journal of Botany
Vol. 50, No. 5 (May - Jun., 1963), pp. 469-476
Stable URL: http://www.jstor.org/stable/2440317
Page Count: 8
  • 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.
Calamocarpon Insignis, a New Genus of Heterosporous, Petrified Calamitean Cones from the American Carboniferous
Preview not available

Abstract

Calamocarpon insignis is described as a new genus of calamitean cone based on numerous fragments of microsporangiate and megasporangiate cones found in coal balls of middle Pennsylvanian age from the Cherokee Group of Kansas and the Des Moines Series of Iowa. The cones are similar to Calamostachys in general construction, having a hollow pith, prominent protoxylem canals, and alternating whorls of sterile bracts and sporangiophores. They differ in that the microsporangiate cones bear microsporangia each containing several hundred microspores which may occur as tetrads or single spores, while the megasporangiate cones bear large rectangular megasporangia each containing a single functional megaspore surrounded by sterile nutritive tissue. The microspores average 30-40 μ in diameter compared to a maximum measurement of 2.7 x 0.7 mm for the single rectangular megaspore. The female gametophyte was produced within the megaspore which was held within the megasporangium during the entire period of development. The megasporangia were deciduous so that the entire structure was shed as a unit.

Page Thumbnails

  • Thumbnail: Page 
469
    469
  • Thumbnail: Page 
470
    470
  • Thumbnail: Page 
471
    471
  • Thumbnail: Page 
472
    472
  • Thumbnail: Page 
473
    473
  • Thumbnail: Page 
[474]
    [474]
  • Thumbnail: Page 
475
    475
  • Thumbnail: Page 
476
    476