Yellow Flatsedge – Cyperus croceus

A large, robust plant of Cyperus croceus growing in a patch of pineland heliotrope (Heliotropium polyphyllum) in my front yard.

Cyperus croceus is a common native perennial that has been recorded from all but 12 counties in Florida. Since it occurs in a wide variety of habitats, including marshes, hammocks, sand scrub, sandhills, flatwoods, and disturbed areas, it likely occurs in every county in Florida. In urban areas, it can be found as a weed of neglected lawns, in fields, and along roadsides. It is also one of a group of natives that occurs spontaneously in my yard, especially in sunny areas where there is exposed soil devoid of mulch. Its common name is usually listed as "Baldwin's flatsedge," which is derived from a synonym for this species: Cyperus baldwinii. I prefer the more descriptive common name of "yellow flatsedge," derived from the species epithet, croceus, which means "saffron yellow." But bear in mind that the spikes are greenish when young, brownish when mature, and only somewhat yellowish for a brief period in between.

Younger, smaller plants have a graceful, rather delicate appearance.

As one can well imagine, a plant that readily grows in both the wet soils of marshes and the dry sand of sandhills, in full sun to light shade, is effortlessly cultivated and it can often be established by simply scattering seeds in an open, sunny area. It is, as far as I know, never intentionally cultivated but I could see it being used as a 1–2 foot (0.3–0.6 meters) tall groundcover in a dry, sandy site where little else will grow well. It adapts very well to being mowed and I have seen lawns consisting mostly of Cyperus croceus in older urban neighborhoods. Wildlife value appears to be limited but it may serve as a larval food plant for Diploschizia impigritella, the yellow nutsedge moth. In wetland areas, its tiny, seedlike fruits are eaten by waterfowl and the foliage may be eaten by geese.

A close-up view of an early-stage inflorescence.

Although it can be a bit weedy, yellow flatsedge grows in clumps and lacks underground rhizomes. Thus, it is easily weeded out by slicing the bottom of the plant from its roots. So long as no vegetative portion remains attached to the roots, it will not grow back. A few plants, here and there, add variety, texture, and interest to native plant gardens and, so long as bare soil is covered with mulch, leaf litter, or other plants, it rarely presents a serious weed problem. However, plants can form sizeable clumps, as seen in the first image above, and so it should be kept a safe distance from small or delicate wildflowers.

Images and text © 2013 Rufino Osorio

Two Flat Sedges – Cyperus haspan and Cyperus odoratus

Cyperus odoratus.

Flat sedges, members of the genus Cyperus, are rarely grown even though 35 native species occur in Florida, along with an additional 19 non-native species. Flat sedges are mostly wetland plants found in moist pine flatwoods, bogs, marshes, swamps, and along the margins of streams, ponds, and lakes. They also occur in artificial impoundments and ditches. A few species occur in dry sandy areas, such as sand scrub. Some species, both native and non-native, are extremely weedy and perhaps this has given the whole genus a bad reputation. Their flowers are individually insignificant and come in various shades of green or brown; however, they are aggregated into often conspicuous, sometimes even attractive, inflorescences.

I am currently growing, as potted plants, two native flat sedges. The first, shown above, is Cyperus odoratus (fragrant flat sedge). It is a common weedy annual found nearly throughout Florida. The second, shown below, is Cyperus haspan (leafless flat sedge). It is unusual in that the leaf blades are usually reduced to an inconspicuous sheath and its culms appear to be leafless. It is a perennial species that, like Cyperus odoratus, is a common, rather weedy, sedge found nearly throughout Florida.

Cyperus haspan

Cyperus haspan

Nearly all flat sedges are effortlessly grown so long as they are provided with moist soil and plenty of sunlight. Usually, their cultivation presents only two significant problems. Each plant is capable of producing hundreds or thousands of seeds, each one of which seems to readily germinate. And flat sedges are identified on the basis of minute, technical, recondite characters and are very difficult for most gardeners to identify. As a consequence, it is often difficult for non-botanists to know whether a given flat sedge is a native species or an introduced, non-native species.

Images and text © 2013 Rufino Osorio