The bands on the walls were an early improvisation to aid the easy flow of water, and served as tracheids, although they are not equivalent in their construction. Banded tubes were lignified, giving them a more rigid structure than hydroids, allowing them to cope with higher levels of water pressure.
Banded tubes have a markedly different ultrastructure from plant tracheids, and display a wide variety of wall structures, which implies that they were produced by a variety of different organisms, or perhaps were widely variable within a single nematophyte-like organism.
Proposed functions include water transport, feeding (cf. fungal hyphae), and anchorage (cf. rhizoids).
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- Niklas, K.; Pratt, L. (1980). "Evidence for lignin-like constituents in Early Silurian (Llandoverian) plant fossils". Science 209 (4454): 396–397. Bibcode:1980Sci...209..396N. doi:10.1126/science.209.4454.396. PMID 17747811.
- Sperry, J. S. (2003). "Evolution of Water Transport and Xylem Structure". International Journal of Plant Sciences 164 (3): S115–S127. doi:10.1086/368398. JSTOR 3691719.
- Edwards, D.; Axe, L. (2012). "Evidence for a fungal affinity for Nematasketum, a close ally of Prototaxites". Botanical Journal of the Linnean Society 168 (1): 1 –18. doi:10.1111/j.1095-8339.2011.01195.x.