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Journal Article

The Adult Cycad Trunk

Charles J. Chamberlain
Botanical Gazette
Vol. 52, No. 2 (Aug., 1911), pp. 81-104
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Page Count: 24

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Topics: Tree trunks, Tracheids, Pith, Plants, Xylem, Phloem, Plant cells, Growth rings, Leaves, Peduncle
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1. The paper deals with field material of adult stems of Dioon spinulosum, D. edule, Ceratozamia mexicana, and Zamia floridana, particular attention being given to Dioon spinulosum. 2. In Dioon spinulosum the xylem zone in a plant 6 meters in height reaches a width of 10 cm., far exceeding the extent of any xylem zone previously described for any cycad. 3. Dioon spinulosum and D. edule have growth rings, which in D. spinulosum correspond to the periods of activity which result in the formation of crowns or cones, but which in D. edule do not correspond to such periods. No growth rings were found in Ceratozamia mexicana or Zamia floridana. 4. Cone domes in the pith were studied in the four species. 5. The histological character of the adult stem was studied in Dioon spinulosum. The protoxylem consists of scalariform tracheids, from which there is a gradual transition to the tracheids with multiseriate bordered pits, constituting the principal part of the wood. There are also cells with the same originas the pitted tracheids, but with transverse walls which may remain thin-walled and contain starch or may become lignified. Besides the leaf trace bundles, scalariform tracheids are found in the large medullary rays. 6. Both in the general appearance of the transverse section and in histological characters the adult trunk of Dioon spinulosum resembles that of Cycadeoidea.

Notes and References

This item contains 9 references.

Literature Cited
  • 1
    BRONGNIART, A., Recherches sur organization des tiges des Cycadees. Ann. Sci. Nat. Bot. I.16:389-402. pIs. 20-22. 1829.
  • 2
    VON MOHL, HUGO, Ueber den Bau des Cycadeenstammes. Abhandl. K. Acad. München 1:397-424. 1832.
  • 3
    METTENIUS, G. H., Beitrage zur Anatomie der Cycadeen. Abh. K. Sachs. Gesell. Wiss. 7:565-608. pIs. I-5. 1861.
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    SOLMS-LAUBACH, H., Die Sprossfolge der Stangeria und der uibrigen Cyca- deen. Bot. Zeit. 48:177-I87, I93-I99, 209-2I5, 225-230. pI. 2. 1890.
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    STRASBURGER, EDUARD, Histologische Beiträge III. 1891.
  • 6
    WORSDELL, W. C., Anatomy of stems of Macrozamia compared with that of other genera of Cycadeae. Annals of Botany10:601-620. pIs. 27, 28. 1896.
  • 7
    CHAMBERLAIN, CHAS. J., Dioon spinulosum. BOT. GAZETTE48:401-4I3. figs. I-7. 1909.
  • 8
    SMITH, FRANCES GRACE, Morphology of the trunk and development of the microsporangium of cycads. BOT. GAZETTE43:187-204. pl. IO. I907.
  • 9
    EAMES, ARTHUR J., On the origin of the broad ray in Quercus. BOT. GAZETTE49:161-I67. pIs. 8, 9. I9IO.