Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in through your institution.

Journal Article

The Reproductive Biology of Totara (Podocarpus totara) (Podocarpaceae)

VIVIENNE R. WILSON and JOHN N. OWENS
Annals of Botany
Vol. 83, No. 4 (April 1999), pp. 401-411
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/42765960
Page Count: 11

You can always find the topics here!

Topics: Embryonic cells, Cell walls, Ovules, Ova, Cell nucleus, Gametes, Cytoplasm, Embryos, Pollen, Mother cells
Were these topics helpful?
See something inaccurate? Let us know!

Select the topics that are inaccurate.

  • Download ($42.00)
  • Add to My Lists
  • Cite this Item
The Reproductive Biology of Totara (Podocarpus totara) (Podocarpaceae)
Preview not available

Abstract

A reproductive cycle of totara (Podocarpus totara) in New Zealand is complete within 2 years. After strobilus initiation in September, there is a 9 month period of winter dormancy until emergence during the growth flush in July-August of the following year. Female strobili bear only one or two ovules which are pollinated mid-October to mid-November at the megaspore tetrad stage. Pollen germination and fertilization occur rapidly during December. The pollen tube carries the body cell, sterile and tube nuclei with at least three prothallial nuclei, and branches out after reaching the archegonia. The four-six archegonia contain egg nuclei with no distinct perinuclear zone and a large chalazal vacuole. Fertilization by the larger of the two unequal male gametes is accompanied by a degradation of egg cell cytoplasm. The three-tier proembryo contains a binucleate embryonal tier of only one cell. Soon after embryo penetration into the megagametophyte, the binucleate embryonal-tier cell undergoes mitosis and cell wall formation resulting in four uninucleate cells. Some ovules contained secondary embryos thought to be the product of suspensor cleavage. Embryo maturation occurs by February.

Page Thumbnails

  • Thumbnail: Page 
[401]
    [401]
  • Thumbnail: Page 
402
    402
  • Thumbnail: Page 
403
    403
  • Thumbnail: Page 
404
    404
  • Thumbnail: Page 
405
    405
  • Thumbnail: Page 
406
    406
  • Thumbnail: Page 
407
    407
  • Thumbnail: Page 
408
    408
  • Thumbnail: Page 
409
    409
  • Thumbnail: Page 
410
    410
  • Thumbnail: Page 
411
    411