Which feature is NOT characteristic of the Paniceae tribe?

The Paniceae tribe, which is part of the grass family (Poaceae), is known for specific morphological features that distinguish its members. One notable characteristic is their growth form; many species exhibit coarse rhizomatous growth, which allows them to spread and establish robust populations in a variety of habitats. Additionally, the inflorescences of Paniceae are typically open and branched, facilitating the exposure of flowers to pollinators and maximizing reproductive success.

Another feature of the tribe includes the structure of the glumes; in many species, the lower glumes may be reduced and sterile. This adaptation can be part of the evolutionary strategies of the tribe, which allow them to allocate resources more efficiently towards reproduction.

In contrast, the notion of having "adventitious roots only" is not indicative of the entire tribe. While some grass species do produce adventitious roots, many species within Paniceae also develop other forms of root systems, including fibrous and perennial roots. Thus, the characteristic of having only adventitious roots does not align with the diverse root types found within the tribe, making it incorrect as a defining feature.