Hello,
Tracheid in Cupressaceae and other conifers may exhibit ornamentation on their walls that resemble helical spiral thickness little bit, as result of an angle in Microfibrils. What is the relation between these two, spiral thickness and "Cellulose Microfibril Angle ". and do conifer form tracheids with any kind of spiral thickness at all or it is Angiosperm specialized trait?
thank you
Hello
it is mostly by the Taxaceae, but also by the Cupressaceae s.l. and the Pinaceae that such thickenings occur. Usually these thickenings are spiral thickenings indeed, but they can also be transversal bars, e.g. like by Callitris. Such thickenings are tertiary thickenings. They are made of cellulose fibrills, in anisotropous layers, impregnated by lignin. When oblique such thickenings are at an angle which is mostly genetically controlled and characteristic. Cellulose microfibrils are also usually oblique, with no special orientation in the primary layer, orientated parallely (anisotropous) in the differents layers of the secondary wall and in the tertiary thickenings. These tertiary thicknenings are usually rather uniform in thickness (not nodular, and of the same thickeness in the different tracheids of a species).
Does this answers your question ?
Hello Marc Philippe,
Thank you for this answer. It was advantageous, especially the first parts clarified what I need.
Thank you
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