Structural and histochemical analyses of the vegetative organs of Eichhornia crassipes

ABSTRACT

Water hyacinth (Eichhornia crassipes), a free-floating aquatic macrophyte belonging to the family Pontederiaceae, is invasive in tropical and subtropical areas worldwide. Using brightfield and epifluorescence microscopy, we investigated the anatomical structures and histochemical features allowing this species to float freely, and to successfully invade aquatic environments. The roots of water hyacinth have a lignified endodermis with Casparian bands and no suberin, as well as a lignified cortex and hypodermis. The stem epidermis is covered with a thin cuticle, and lignified sclerenchyma delimit the central cylinder with scattered vascular bundles. Air spaces, which included schizogenous intercellular spaces and lysigenous aerenchyma, were observed in the root cortices, while schizo-lysigenous aerenchyma and protoxylem lacunae were observed in the shoots. Key structural features of the water hyacinth, including barriers (e.g. the endodermis, lignified cortex and hypodermis, and cuticle) and air spaces, may allow this plant to float freely and to invade aquatic environments. Thus, our study identified the anatomical features that allow the water hyacinth to thrive in aquatic environments.

KEYWORDS:

• Cuticle
• endodermis
• lignified cortex
• lysigenous aerenchyma
• schizo-lysigenous aerenchyma

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contributions

All authors contributed to this study design, conception and data collection. Cunyu Zhou characterized the morphological, anatomical and histochemical alternations and wrote the manuscript. Xia Zhang, Yongbing Guo, Shuangshuang Hu, Yu Tang, Teng Li and Ting Wang assisted stain solution preparation. Guofei Ma and Chaodong Yang prepared cross sections and analyzed the root anatomical structures and histochemical components. Cunyu Zhou supervised the experiments and revised the manuscript. All authors read and approved the final manuscript.

Additional information

Funding

This work was supported by Hubei Province Key Laboratory of Conservation Biology for Shennongjia Golden Monkey Opening Fund (2019SNJ003), Engineering Research Center of Ecology and Agriculture Use of Wetland (Ministry of Education) Opening Fund (KFT202004) and Major Program on Technology Innovation of Hubei Province (2018ACA132) and (2019ACA162).