This has increased in North America along with angustifolia, and it has been considered an incipient species by several authors (F, RAB, W). In Ky. these apparent hybrids are locally abundant and deserve to be mapped, but most colls. need further checking; see FNA 22 for detailed key. There could also be confusion with domingensis, if this is present; see notes under that name. The potential role of mammalian herbivores in influencign Typha abundance desevres deep investigation. In New York, Rawinski & Malecki (1984) found that muskrats coul reduce T.x glauca but this allowed Lythrum salicaria to increase; Grazing by deer had little effect.