This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Marsh plants, or Helophytes as they are called, are unlike aquatic plants in that though their roots grow in water-logged soil in which there is 80 per cent of water, yet their stems are never quite submerged and are usually erect, many aquatic plants being submerged and lying on the surface of the water. They usually grow in shallow water, if submerged at all, and in still or but little disturbed water.
Most of the marsh plants are perennials, and a large number have creeping rhizomes, such as Phragmites or Reed, Reed Mace, Iris, Yellow Flag, Flowering Rush, Bulrushes, Cotton Grass, Bur Reed, Sedges, etc. Some are tufted, as Purple Loosestrife, Water Plantain, also members of aquatic vegetation, and they build up a layer of dead stems growing from the topmost aided by the capillarity of the dried stems and water, as in the case of the Tussock Sedge. They contain air-spaces as in Rushes. Many have the mesophytic habit, and others are Xerophytes. The seeds contain air-spaces, which assist in dispersing them by water.
Two types of formation may be recognized at least, and there are probably others. Many indeed are amphibious, growing half on land half in water. The two recognized formations are the Reed formation and the Bush Swamp formation.
In classifying the marsh and water plants, we have regarded as belonging to the latter all the plants which grow in or by the sides of lakes, rivers, streams, and ditches, and have reserved for the marsh plants those that grow mainly in true bogs or marshy tracts that are separate or can be distinctly marked off from the latter. In this way, while Reeds are included in Section VIII (and some others here mentioned which occur in Section VIII), they are equally marsh plants. The grouping by Lakes, Rivers, Streams, etc, is partly artificial (just as in the case of roadside plants), for the benefit of the touring botanist, who can better follow such classifications than the cut-and-dried divisions into Hydrophytes, and, as here, Helophytes. With the Reed in the Reed formation one finds Bulrush, Reed Mace, Flowering Rush, Iris, Galin gale, Hummock Sedge, Water Plantain, Arrowhead, Bur Reed, Great Hairy Willow Herb, Great Yellow Loosestrife, Sweet Flag, Buckbean, Purple Loosestrife, Great Spearwort, Water Dropwort, etc.
Zones can be recognized, moreover, in this formation named after the dominant species or genus, such as phragmiteta, scirpeta, heleo-chareta, cariceta, typheta, equiseteta. The Hydrophytes are tall, slender, and upright, usually unbranched. As will be seen some of those that grow in true bogs, requiring acid humus, must also be considered Oxylophytes, and high- or low-moor plants. Some parts of marsh and bog land are covered or interspersed with shrubs or trees, one or more of which give to each type a character of its own. Such are Alneta, where one finds Purple Loosestrife, Meadow Sweet, Buck-bean, Sedges, Willows, Guelder Rose, and the Nettle.
Saliceta, on banks of swamps, are characterized by the Crack and White Willows, Great Yellow Loosestrife, Great Hairy Willow Herb, Valerian, Meadow Sweet, etc, with Reeds, and higher up, Bittersweet, Great Bindweed, and Hop. In other places, Betuleta and Pineta are characterized by the dominance of Birches and Pines with their own ground flora.
Out in the midst of the pools rises the tall, graceful, and stately Great Spearwort. Its yellow chasubles shine like melted gold in the sun. Down by the sides of the meres, and in wet marshy meadows, Kingcups play a kindred part. Here, too, the lovely white, veined petals of the Grass of Parnassus, with the scale-like honey glands, spot the meadows in autumn, where the Bog Bean and Marsh Helleborine lie hid amongst the mulchy sedges and moist undergrowth. In the little bog-pools the insectivorous Sundew glistens like sparkling drops of dew in the sun, to attract its insect prisoners, rare viands for a plant!
Diminutive forests are formed by the Water Dropwort, which grows, like Valerian, in low-lying meadows, forming dense undergrowth, with flowers pure and white. On the moors or in wet bogs the Cranberry and Wild Rosemary, in less upland morasses, are found here and there, the first being sought after eagerly for its fruit in autumn. Bog Pimpernel, with its choice pink blossoms, trails in the moist hollows close by where Water Violet swims in the quiet pools, anchored only by its webwork of foliage. Crouching low down amid the sedges and rushes the Bog Speedwell is a true marsh species, and Marsh Lousewort grows on the borders of moist meadows where Bog Bean flourishes.
Photo. I. R. J. Horn.
Broad Or Shallow Lagoon With Aquatic Vegetation Showing floating leaf associations covering the surface. Marginal to this is a fen association, which gradually encroaches on the aquatic vegetation, with a thicket scrub of Sweet Gale, Willow, etc.
The shiny leaves and uncommon flowers of the Butterwort are a peculiar feature in the same habitat as Sundew. In upland pools, quite immersed save for the erect flower-stalks, grows the quaint Bladderwort, which, like Sundew, is insectivorous. In favoured spots the Bog Bean flowers, but not everywhere. Golden Dock invades many an inland marsh with its tall golden panicles of yellow flowers. Bog Myrtle grows in upland bogs with Asphodel, which makes the moors bright golden-red in autumn here and there. White Willow lines the sides of the marshes with its silvery foliage glistening in the sun. Amongst wet sedges and herbage Marsh Orchis rises with its pink blooms, encircling the green expanse with its choice colour. The sedges and rushes, etc., include common Joint-rush, Galingale, Common Spike Rush, Cotton Grass, Prickly Twig Rush, Hummock and Great Prickly Sedge.
There are about 250 paludal plants, and we have described twenty-eight in this series.
For further general notes on Marshes and Bogs, see Heaths and Moors, and "Hints and Notes" on both sections; and also Section I, Vol. I, where an alternative grouping is considered.