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Pith helmets adrift and rootwood from the Swamps

Pith helmets adrift and rootwood from the Swamps. Pieter Baas, Bertie-Joan van Heuven & Nancy Vander Velde. Contents. Mysterious driftwood from the Marshall Islands Identification of mystery rootwood A royal wood sample from Tervuren Two pith helmet samples from Kew

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Pith helmets adrift and rootwood from the Swamps

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  1. Pith helmets adrift and rootwood from the Swamps Pieter Baas, Bertie-Joan van Heuven & Nancy Vander Velde

  2. Contents • Mysterious driftwood from the Marshall Islands • Identification of mystery rootwood • A royal wood sample from Tervuren • Two pith helmet samples from Kew • Peculiar wood structures in swamps and inundation forests • A mysterious trunk of “Balsa” in Leiden

  3. Nancy Vandervelde sitting on driftwood

  4. Traditional use of Light Driftwood • Cheap Cork substitute (plugs for coconut shell containers and orifices of prepared human corpses). • Pillows • Model canoes • Called Wuj´ • Replaced by styrofoam in modern times!

  5. Drftwood TLS Laticifer

  6. Unusual features of driftwood • Parenchyma-like fibres with numerous vestured pits and no intrusive tip growth • Vestured fibre pits without borders • Very low and narrow rays • Sporadic laticifers in rays • Marginal parenchyma (distinct ring boundaries!) • Very few and very narrow vessels

  7. Stem and Rootwood of Alstonia spatulata Lowland swamp forest tree in the Indo-Pacific from Thailand to New Guinea Ingle & Dadswell 1953

  8. Uses of A.spatulata rootwood • Pith Helmets • Cork substitute • Rafts • Trade names include: Siamese Balsa • Rootwood of Alstonia pneumatophora and Dyera spec. (Apocynaceae)has similar uses

  9. Alstonia spatulata stemwood

  10. Wood Sample of Alstonia spatulata from Tervuren Xylarium Collected by: His Majesty King Leopold III of Belgium

  11. Leopold III

  12. Leopold III

  13. Kew Samples of A. spatulata • Vestured pits present! • Laticifers – none seen • Growth rings distinct

  14. Rootwood (above) Stemwood (below)

  15. Rootwood variables • Fibre diameter and length • Ray height and width (1-seriate) • Vesturing of fibre and vessel pits • Vessel diameter and frequency • “Growth ring width” • Laticifer density (zero to very low)

  16. Functional Speculation • Growth rings reflect inundation cycles! • Thin-walled tissue & lack of fibre elongation reflect lack of mechanical function! • Fibre wall deposition is too limited to complete pit borders of vestured pits! • Very wide fibres for water storage and/or as subsidiary conducting cells !?

  17. Wood of Swamp Forest Trees in Perspective • Alex Wiedenhoeft finds comparable patterns in Amazon inundation forest species from 5 different plant families • Peculiar wood anatomy of Leptospermum crassipes from swamp flats in Australia recalls that of A. spatulata • Conclusion: xylem structure of swamp trees and shrubs shows convergent adaptation and its development and functions deserve further study.

  18. Leiden “Balsa” wood sample (= A. spatulata!) Base has rootwood; distal part intergrades towards stemwood Q to You: How can trees survive on such a mechanically weak and hydraulically unfit base?

  19. “Balsa wood”

  20. Section Alstonia A. scholarisA. boonei Monuraspermum A. spectabilis Wood Anatomy follows monophyletic sections in Alstonia

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