Title: Morphology of gymnosperms
Identifier: cu31924058797063 (find matches)
Year: 1917 (1910s)
Authors: Coulter, John Merle, 1851-1928; Chamberlain, Charles Joseph, b. 1863; Coulter, John Merle, 1851-1928. Morphology of spermatophytes. Part I. Gymnosperms
Subjects: Gymnosperms; Plant morphology
Publisher: Chicago, University of Chicago Press
Contributing Library: Cornell University Library
Digitizing Sponsor: MSN

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
BENNETTITALES 79 erous region only interseminal scales occur; above this there are usually five or six scales packed around each seed pedicel (fig. 65). The scales are slender (filiform) at base and gradually thicken upward in prismatic form to the seeds, where the faces are hollowed to receive them. Above the seeds the scales enlarge again and their tips form a complete mosaic, perforated only by the micro- pylar tubes. In the group of species with more or less elongated receptacles, as Cycadeoidea dacotensis (fig. 66), the nu- merous scales and pedicels are relatively short and of uniform length, so that in a young stage the conical tip of the axis, as WiELAND suggests, appears like a brush. There are two interpreta- tions of these scales and pedi- cels. LiGNiER (25) maintains that the scales are bracts in whose axils the pedicels appear; and that therefore the pedicel is an axial structure bearing an ovulate "flower" reduced to its lowest terms. This view necessarily regards the strobilus of Bennettitales as an "inflo- rescence," which, in so far as it means a compound (branching) strobilus, is represented among gymnosperms by the ovulate strobih of certain of the Pinaceae and by both strobili of the Gnetales. The same investigator (19) has also satisfied himself, by an examination of Bennettites Morieri, that in all the scales which enter into the composition of the strobilus the terminal enlargement is due to hypertrophy and is not a reduction stage.
Text Appearing After Image:
Fig. 63.—Bennettites Gibsonianus: dia- gram of seed-bearing strobilus; the seeds, each containing a dicotyledonous embryo, are borne on long pedicels; between the seeds are the interseminal scales with dilated ends; surrounding seeds and scales are overlapping bracts.—Modified by Scott (io) after Solms-Laubach (5) and Potonie (6a).

Note About Images