He latter are mixed associations, such as fens, where different :cies are produced by the varying abundance of characteristic ants, such as Cladium Mariscus, Phragmites communis, Molinia~ erulea, Calamagrostis lanceolata, and Juncus obtusiftorus.
Marsh plants: Alopecurus geniculatus, Carex dis~icha, Juncus spp., Caitha palustris, Nasturtium palustre.
With regard to the occurrence of plants, such as Juncus effusus, which possess xerophytic characters and yet live in situations which are not ordinarily of marked physiological dryness, it should be remembered that such habitats are liable to occasional physical drought; and a plant must eventually succumb if it is not adapted to the extreme conditions of its habitat.
The xerophytic characters being present, it is not surprising that many marsh plants, like Juncus effusus and Iris pseudacorus, are able to survive in dry situations, such as banks and even garden rockeries.
It is well represented in Britain by the two genera which comprise nearly the whole order - Juncus, rush, and Luzula, woodrush.
They are generally perennial herbs with a creeping underground stem and erect, unbranched, aerial stems, bearing slender Juncus effusus, common rush.