Structural features of Phalaris arundinacea in the Jianghan Floodplain of the Yangtze River, China

- Phalaris arundinacea is an invasive grass in the Jianghan Floodplain of China.
- Adventitious roots, rhizomes and culms are mostly typical of wetland grasses.
- Rhizomes have endodermis and culms have exodermis, not present in most grasses.
- Aerenchyma occurs in roots and pith and cortical cavities in rhizomes and culms.

We examined reed canary grass, Phalaris arundinacea, under shallowly flooded conditions along the Jianghan Floodplain of the Yangtze River to determine structural traits with an emphasis on histochemistry of cell walls in endodermal, exodermal, and epidermal layers and to determine if these traits are consistent with those of other wetland plants of the Floodplain. Roots have an endodermis with Casparian bands, suberin lamellae, and secondarily lignified walls. Outside schizo-lysigenous aerenchyma of the cortex, a biseriate exodermis has Casparian bands and suberin lamellae and lignified walls, and often an internal suberized layer is present. Rhizomes have a thick cuticle, lignified peripheral mechanical ring with an exodermis, large cortical cavities, an endodermis delimiting a central cylinder and sclerenchyma ring, and pith cavities. Culms with leaf sheaths have a thick cuticle and an exodermis in a narrower peripheral mechanical ring, small cortical cavities, a central cylinder with a sclerenchyma ring and pith cavities, but no endodermis. Most vascular bundles are located in the central cylinder and its sclerenchyma ring. These structural features of reed canary grass are characteristic of plants adapted to the seasonal flooding of the Floodplain below the Three Gorges Reservoir Region of the Yangtze River in China.