Editing Phloem (section)

===Supportive cells===
Although its primary function is transport of sugars, phloem may also contain cells that have a mechanical support function. These are sclerenchyma cells which generally fall into two categories: fibres and sclereids. Both cell types have a [[secondary cell wall]] and are dead at maturity. The secondary cell wall increases their rigidity and tensile strength, especially because they contain [[lignin]].{{cn|date=January 2025}}

====Fibres====
[[Bast fibre]]s are the long, narrow supportive cells that provide [[Tension (physics)|tension]] strength without limiting flexibility. They are also found in [[xylem]], and are the main component of many textiles such as paper, linen, and cotton.<ref name="Raven et al. 1992" />

====Sclereids====
{{Main|Sclereid}}
Sclereids are irregularly shaped cells that add compression strength<ref name="Raven et al. 1992" /> but may reduce flexibility to some extent. They also serve as anti-herbivory structures, as their irregular shape and hardness will increase wear on teeth as the herbivores chew. For example, they are responsible for the gritty texture in pears, and in winter pears.<ref>{{Cite journal |last1=Martin-Cabrejas |first1=Maria A. |last2=Waldron |first2=Keith W. |last3=Selvendran |first3=Robert R. |last4=Parker |first4=Mary L. |last5=Moates |first5=Graham K. |date=1994 |title=Ripening-related changes in the cell walls of Spanish pear (Pyrus communis) |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1399-3054.1994.tb03004.x |journal=Physiologia Plantarum |language=en |volume=91 |issue=4 |pages=671–679 |doi=10.1111/j.1399-3054.1994.tb03004.x |bibcode=1994PPlan..91..671M |issn=0031-9317}}</ref>