| Their internal stem structure is characterized by a eustele with endarch protoxylem, where a small amount of manoxylic wood is produced from a bifacial vascular cambium. |
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| They have narrow phloem strands adjacent to large, single, permanent protoxylem or metaxylem elements. |
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| Tracheary element secondary wall patterns and the definition of protoxylem and metaxylem. |
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| Protoxylem tracheids have helices with borders in Huperzia and Lycopodium, but in Phylloglossum protoxylem annuli and helices are non-bordered. |
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| Embolisms and refilling in the maize leaf lamina, and the role of the protoxylem lacuna. |
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| At the same time many secondary walls of the tracheal elements, first formed from the protoxylem, are deposited in the form of rings. |
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