Dean P. Whittier

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Pteridium gametophytes cultured on a medium containing 4% sucrose under various qualities of light exhibit different developmental responses. Under far-red illumination (690–730 nm) apogamy is produced without enhanced gametophytic growth, thus allowing a distinct separation of the specific induction of apogamy from a general enhancement of gametophytic(More)
In this correlated SEM (scanning electron microscope) and TEM (transmission electron microscope) investigation, we describe architectural details of the multiflagellated sperm cell of Psilotum nudum. Comparisons with other pteridophytes are made to (1) assess the placement of Psilotum among pteridophyte taxa and (2) evaluate structural modifications of(More)
Mature, gametangia-bearing photosynthetic gametophytes of Phylloglossum can be grown from the nonphotosynthetic, cylindrical, negatively gravitropic immature stages in illuminated axenic culture on a nutrient medium with or without 0.2% glucose. The gametangial-bearing region of these gametophytes, the photosynthetic crown, grows horizontally from the apex(More)
BACKGROUND AND AIMS Long-lived underground populations of mycoheterotrophic gametophytes and attached sporophytes at various developmental stages occur in lycophytes. Young underground sporophytes obtain carbon solely from the gametophyte and establish nutritional independence only after reaching the soil surface, which may take several years. This(More)
The level of induced apogamy in gametophytic colonies of Pteridium aquilinum (L.) Kuhn is altered by varying the number of colonies per culture vessel or by including a constant number of colonies in culture vessels of different volumes. In either case, placing vials of mercuric perchlorate, an absorber of ethylene, within the closed culture vessels reduced(More)
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