Wet, marshy land is not terribly hard to find in Iowa. Most are easily announced by their tall, gracefully swaying cattails. Cattails (Typha latifolia) spread by thick rhizomes under the soil and create an extensive network of fibrous roots. Cattails are especially drawn to wet marshy areas, more specifically - wet, marshy, nitrogen rich soil. They are commonly found in areas like sloughs in farm fields, farm ponds, and drainage ditches.
At first glance, cattails, with their long thick leaves and their decorative brown seed heads are very interesting. However, if you watch carefully, you can almost see them growing and spreading. The most impressive thing about the cattails is that they are very invasive. A small clump of the showy foliage is great, but you will soon find yourself with more than you can handle. Fortunately, there are other plants that can be used as wetland plants that are just as impressive and not as invasive.Iris pseudacorus (yellow flag) or versicolor (blue flag) are both beautiful types of iris. These iris have showy flowers in the spring and lovely thick, dark green leaves. As their common names indicate, yellow flag and blue flag produce yellow and blue flowers respectively. Both types of iris are very hardy (USDA hardiness zones 3-9) and can grow in streams and marshes with full to partial sun. Though native to coastal areas in the southern United States, Louisiana irises are hardy in zones 4-9. They are valued for their colorful white, blue, red, and yellow flowers. Equisetum hyemale or horsetails as they are commonly called can be used to create an interesting texture within any water garden. They are native to Iowa and can spread quickly. The 1-2 foot tall stalks have a rough texture to them and have only small scales at the nodes for its leaves. They are otherwise tall, narrow, tubular stems.Acorus calamus is commonly called sweet flag. It is a light green colored reed-like plant that is found throughout the state. It is hardy in zones 4-9, and one of its more intriguing qualities is the spicy fragrance released when the foliage is crushed or broken. Another interesting feature is the flowering structure of tiny flowers that are produced on a brown spadix that forms on the side of the reed during mid to late summer. 'Variegatus' is a cultivar with variegated green and white foliage.
There are a variety of sedges that can also be planted for wetlands to provide height and texture. The red root flat sedge (Cyperus erythrorhizos) has a shorter stem of only 2-3 feet tall, but has an extraordinary reddish brown seed head. Scirpus atrovirens (dark green bulrush) is another common sedge that has a rather showy seed head that is 4-5 feet tall and very hardy for this area.
Rushes are also nice natural looking plants for wet areas. Juncus acuminatus is an example, it is otherwise known as the tapertip rush and has a showy red to pink flowering seed head. Plants are 3-4 feet tall and are hardy in Iowa. Wild rice is another alternative as well. Zizania aquatica is a tall grassy plant, up to 10 feet tall, with long, white plumes of seeds. Though rare, wild rice is native to northeast Iowa. Elymus canadensis is a distant relative of rice called Canada wildrye. It is unique in that this 5-6 foot tall grass has arching spikes of seed heads with twisting awns. Pontederia cordata, commonly called pickerel weed is a fantastically showy plant with its unusual heart shaped leaves and blue/purple flowering stalk. It is hardy in zones 4-9 and requires full to part sun. This native plant can be in a stream or shallow pond, but it will only get up to 2 feet tall.Sagittaria latifolia or arrowhead plant is also a good plant for sunny spots in a stream or pond. The 4-5 foot leaves usually draw attention because of their unusual shape, an arrowhead with smooth edges. Its blossoms are white and are commonly seen in northeast portions of Iowa. The arrowhead plant is native to this state.Alisma plantago aquatica or water plantain is yet another wonderful plant for wetlands. This plant grows in a rosette, or clump formation and can reach up to 3 feet tall with a tall panicle of delicate white flowers that make it nearly 6 feet tall. This plant is hardy (zones 4-8) and grows well in sun to part shade. Ranunculus lingua is otherwise known as the greater spearwort, and with its captivating yellow flowers it is easily incorporated into any ornamental pond or stream garden. It is hardy (zones 4-8) and can grow as tall as four feet. The thin, graceful leaves and stem of this plant make it especially attractive.Calla palustris is a nice low growing water plant that is also known as water arum. It has dark green heart-shaped leaves and produces a white spathe that will develop red and orange fruit as it matures. This plant is hardy (zones 3-8) and grows in the full sun along streams and in ponds.
All of the aforementioned plants are considered emergent plants. This means that they have roots in the water that anchor them, and their leaves and stems are above the water. The majority of these plants are perfect for any slow moving water garden or pond. The reeds and sedges will create a natural look, and their showy seed heads will captivate those looking for more than just green stems and leaves. The dicots are a welcome addition as well and will produce flowers and fruits that will add color and contrast to the tall, grace of the monocots. By combining the monocots and the dicots in your garden you will be able to develop a more ornamental looking stream garden or pond, as opposed to the ever popular cattail ditch-look.
This article originally appeared in the August 13, 1999 issue, pp. 110-111.