Wood Anatomy of Chenopodiaceae (Amaranthaceae s.l.)

Abstract

The wood anatomy of the Chenopodiaceae is distinctive and fairly uniform. The secondary xylem is characterised by relatively narrow vessels (<100 μm) with mostly minute pits (<4 μm), and extremely narrow vessels (<10 μm intergrading with vascular tracheids in addition to “normal” vessels), short vessel elements (<270 μm), successive cambia, included phloem, thick-walled or very thick-walled fibres, which are short (<470 μm), and abundant calcium oxalate crystals. Rays are mainly observed in the tribes Atripliceae, Beteae, Camphorosmeae, Chenopodieae, Hablitzieae and Salsoleae, while many Chenopodiaceae are rayless. The Chenopodiaceae differ from the more tropical and subtropical Amaranthaceae s.str. especially in their shorter libriform fibres and narrower vessels. Contrary to the accepted view that the subfamily Polycnemoideae lacks anomalous thickening, we found irregular successive cambia and included phloem. They are limited to long-lived roots and stem borne roots of perennials (Nitrophila mohavensis) and to a hemicryptophyte (Polycnemum fontanesii). The Chenopodiaceae often grow in extreme habitats, and this is reflected by their wood anatomy. Among the annual species, halophytes have narrower vessels than xeric species of steppes and prairies, and than species of nitrophile ruderal sites.