Cyperus odoratus

I recently published a post discussing the differences between two commonly confused species in the genus Cyperus, C. esculentus and C. strigosus.  In that post, I mentioned a third species that can be confused with these, C. odoratus.  After seeing C. odoratus today, I thought it would be useful to include some photos of this species for comparison with the previous two.


Cyperus odoratus inflorescence

The spikelets of C. odoratus are similar in color to those of C. esculentus, often having an orangeish hue, turning brown upon maturation.  The spikelets are often more dense in the inflorescence than in C. esculentus, but not as densely packed as those in C. strigosus.

Three Cyperus odoratus spikelets

As in C. esculentus and C. strigosus, the spikelets of C. odoratus consist of several flowers, each of which is subtended by a scale.  Each scale is similar in length to those of C. esculentus, ranging from approximately 2-3 mm (the scales of C. strigosus are 3-4 mm long).

The spikelets of Cyperus odoratus disarticulate below the scales of individual flowers (Steve Sass hand model)

One of the main morphological differences between C. odoratus and C. esculentus is that, when mature, the spikelets of the former disarticulate below each scale, whereas those of the latter disarticulate at the base of the lowest flower only.  To see this, pull on the end of the spikelet and see if it breaks off somewhere along the spikelet (C. odoratus) or if the entire spikelet breaks off as a unit (C. esculentus).  Be sure to try this with numerous spikelets, not just one.

Base of Cyperus odoratus

Yet another way to distinguish between C. odoratus and C. esculentus is to look at the base of the plant.  In the former, there aren't many leaves coming from the base of the plant, whereas the leaves in the latter are heavily basally disposed.  In addition, C. odoratus does not produce the tubers often produced by C. esculentus.

Two Common (and Commonly Confused) Cyperus

The graminoids (mostly the grasses, sedges, and rushes) have a reputation for being difficult to identify to species, but it really just takes some time and understanding of the parts that the keys are describing.  The families should be easy to distinguish.  Rushes (Juncaceae) have sepals and petals (or collectively tepals) surrounding the pistil and stamens, giving them, on a minute scale, the look of a "typical" regular flower such as a lily.  Grasses (Poaceae) and sedges (Cyperaceae) have flowers that are evolutionarily advanced and consist of just the most important parts for reproduction, the pistil and the stamens; the perianth is highly modified in these families and doesn't look like what you would think of as petals and sepals.  In the grasses, the flower is usually subtended by two bracts, known as the lemma and palea, and each floret (as these structures are known collectively) or group of florets is subtended by additional bracts known as glumes (usually two, sometimes one or absent).  In the sedges, the flower is subtended by a single bract, called a scale.  Grasses (nearly all of them, at least) have hollow stems with solid nodes.  Most sedges have solid or pith-filled stems without swollen nodes.  Most grasses have overlapping sheaths; sedges have fused sheaths.  Grass leaves are typically flat or rolled; sedge leaves are usually V- or W-shaped in cross-section.  There are other differences, but understanding these basic differences should at least get you in the right family.

As far as sedges go, Carex is the most diverse genus.  Being able to recognize groups or sections of the genus that have similar characteristics is often a very helpful tool because it allows you to narrow down your species options substantially.  Some of the other more species rich genera in the family Cyperaceae include Scirpus, Eleocharis, and Cyperus.  In the genus Cyperus, the flowers are perfect and there are no perigynia (paper-like sacs surrounding the female flowers) as there are in the genus Carex.  The scales subtending the flowers in Cyperus are folded in half, not flat or rounded as they are in many other genera.  Morphologically, the genus that looks most similar to Cyperus in the United States is Dulichium.  The flowers on plants in the genus Cyperus lack the long persistent styles (the tubercles) that are present in flowers on plants in the genus Dulichium, and Dulichium has axillary inflorescences whereas Cyperus has terminal inflorescences.

Within the genus Cyperus, as within the genus Carex, the species can be organized into several natural groups (subgenera) that share morphological characteristics.  Within subgenus Cyperus, which has flowers with three stigmas (as opposed to two), spikelets along a conspicuous rachis (as opposed to being in digitate or glomerulate heads), and rachilla (the axis to which the flowers are attached) that disconnect from the rachis (the axis to which the spikelets attach) only at the base (as opposed to having rachilla that disconnect beneath each scale), two of the most commonly confused species in the Great Lakes region are Cyperus esculentus and Cyperus strigosus.  Cyperus odoratus is also often confused with these two species, but it is taxonomically placed into subgenus Diclidium because the rachilla disconnect beneath each scale, not at the base of the spikelet.  If you pull on a spikelet of a species in subgenus Diclidium from the end of the spikelet, the spikelet will break somewhere in the middle; pulling on a spikelet of a species in subgenus Cyperus from the end of the spikelet will result in the entire spikelet being removed from the rachis in an intact unit.


Cyperus esculentus inflorescence and leaves

With all of that background information, now we can look at Cyperus esculentus versus Cyperus strigosus to see the differences between these commonly confused sedges.  First take a look at the inflorescences.  Usually, Cyperus esculentus has spikelets that are orangish in color (see photo above), as compared to the yellowish or straw-colored spikelets of Cyperus strigosus (see photo below).  In addition, the spikelets of Cyperus esculentus aren't usually packed into the inflorescence as tightly as those of Cyperus strigosus.

Cyperus strigosus inflorescence

Next, let's look at the scales subtending each flower in the spikelets.  In the two photographs below, the structure in my hand is a  single spikelet, made up of several flowers, each subtended by a scale.

Cyperus esculentus spikelet

Without a ruler for scale, it's a bit difficult to see the difference in the length of the floral scales.  However, you should be able to tell that in the Cyperus esculentus spikelet photo (above), the scales are shorter (approximately 2-3 mm long) than those in Cyperus strigosus (3-4 mm long).  Although this difference isn't much, with some experience, you can begin to notice the short scales of Cyperus esculentus and the "long" scales of Cyperus strigosus on a quick inspection with a hand lens.

Cyperus strigosus spikelet

Yet another difference in the two species can be seen by looking at the base of the plants.

Base and roots of Cyperus esculentus

In Cyperus esculentus, the base of the plant (where the stem meets the roots) is soft and lacks a bulb (see photo above).  Often, at least later in the season, you can find tubers at the ends of some of the roots.  In contrast, Cyperus strigosus has a distinctly bulbous base (see photo below) and lacks any tuberous protrusions on the roots.

Base and roots of Cyperus strigosus

Another difference between the two species that can somewhat be seen in the first set of photos is that Cyperus esculentus is leafy at the base, whereas Cyperus strigosus is not leafy at the base.  In the first two photos, you can see a lot of leaves in the Cyperus esculentus photo, but the leaves are mostly absent in the Cyperus strigosus photo.  The foliage of Cyperus esculentus is also usually shiny and yellow-green, whereas that of Cyperus strigosus are not as shiny.

Honoring Emma Bickham Pitcher (again!)

Rough Sand Sedge, Cyperus schweinitzii, scribes a series of nearly concentric arcs in Porter County, Indiana. Sand arcs like these, along with any kind of gentians, were favorite photo subjects of Emma Pitcher and they always remind me of her.

"Bickie" was an excellent naturalist in the Indiana Dunes region. She was remarkably observant and very sensitive to subtle detail and beauty. After she moved to Michigan, several of her well-written essays were compiled into a delightful book entitled "Of Woods and Other Things (Beach Leaf Press, Kalamazoo, 1996). Earlier I posted some of my favorite quotes from the birding section of the book. Here are my favorites from the botany section:

[Re: Dandelions]: Every spring dandelion battles are enjoined again. Are you for or against them? Are you for strong sprays and a country club lawn? Or for letting Mother Nature have her way? She’ll sprinkle your lawn for free with golden yellow blossoms. The soil will have no chemicals and be full of worms…”

[Re: orchids]: “Let us all look at orchids long and appreciatively and let them be.”

[Re: Wild Cucumber]: “One of my favorite nature pleasures is to pick a two-inch fruit when it is dry and carefully remove bits of outer skin. Underneath I find a reticulated tissue of incredibly fine spun gold.”

[Re: Juneberry or Serviceberry]: They flower when the outdoors is still brown and dreary. It warms the heart to find delicate wispy white petals scattered over prevailing bleakness… It is hardy in southern Michigan, adapts to all soils, blossoms profusely, and bears tasty fruit enjoyed by humans and our feathered friends alike.”

[Re: white oak]: In contrast to most oak species, this acorn is ripe by its first autumn instead of the usual second season.”

[Re: Basswood or American Linden]: Pistils are almost lost among stamens but develop into woody nutlets attached to long leafy bracts. These act as parachutes when seeds are ready to drop. Basswood nectar is a favorite of bees and honey from it is considered unexcelled in flavor.”

[Re: Thuja occidentalis]: “The name arbor vitae originated with Frenchmen in Jacques Cartier’s St. Lawrence River expedition who were stricken with scurvy. Friendly Indians gave them tea brewed with Vitamin C-rich branchlets of this cedar which cured their condition. Thus, the name tree of life was born.” In a glacial relict Indiana bog, the state’s only known site for this tree, the hundred or so white cedars appear to be root sprouts from older trees. There are no young ones.”

[Re: Liriodendron tulipifera]: "Fossils from the Upper Cretaceous era, 70 to 100 million years ago, indicate that this tulip and a Chinese cousin are the only Liriodendrons to survive the Ice Age. European species were wiped out by the glaciers.” A detail that never fails to attract me is the way leaves unfold. Terminal buds are flat, shaped like a duck’s bill. When stipules (parts of the bill) separate, a curled-over leaf folded exactly on the midrib straightens out and unfolds, revealing a perfectly shaped miniature leaf. At its base inside the stipules is another duck’s bill which also opens to disgorge another curled-over, folded-down-the-midrib leaf, and so on and so on, ad infinitum. Plant some tulip trees on your property as a unique gift of shade and ornamental beauty for your descendants.”

[Re: Juglans nigra, American Black Walnut]: "Their foliage is the favorite food for the ethereal pale green luna moth. Trees grow rapidly and are a valuable crop to plant if you have timber harvesting in mind. Black walnut wood is scarce, hardly available at any price. Friends have planted large acreages with black walnut as an inheritance for their children. Will these be more reliable than a stock portfolio?”

[Re: Hamamelis virginiana, Witch Hazel]: “Everything else in the woods is going to sleep in the frosts and cold of October and November when witch hazel is in full blossom. We found lingering petals on a Christmas day stroll.”

[Re: Birches]: “Now that leaves have fallen, it’s fun to look around, study trees, and observe their distinctive characteristics.”

[Re: Fraxinus americana, White Ash]: "Ash branches are also opposite, an occurrence in only a few tree families. If leaves and branches are arranged alternately, the tree is not in these families. Such characteristics are particularly useful in winter when other clues are scarce. A handy phrase to help you remember opposite arrangements in woody plants is MAD-Cap-Horse: Maple Ash Dogwood-Caprifoliaceae-Horse chestnut. (Caprifoliaceae: the honeysuckle family). Francois Andre Michaux, a Frenchman who botanized in North America from 1785 to 1797, wrote that a a leaf rubbed on a bee sting or mosquito bite relieves itching at once. Worth trying, isn’t it?”

[Re: Marvels of Design and Pattern]: "Soft antennae of moths are as delicate as the infinitely fine feathers which make up a bird’s eye ring.”

[Re: Sorghastrun nutans, Indian Grass]: “In Where the Sky Began, John Madson wrote about midwestern prairies: A big patch of tall Sorghastrum is the ultimate playground. The kids are safely lost in deep grass that soaks up their noise and energy, finally spewing them out tired, quieter, and almost human. Another plus for prairie.”

[Re: Spring]: "Ever since winter solstice, days started lengthening and small changes are occurring in our natural world. Skunk cabbages sent up tightly furled green leaf cones last September. Now that their strange internal furnaces are activated, dark red flower spathes are forcing up through ice and snow. (Air inside the spathe can be as much as fifty degrees warmer than outside air, so great is the heat the root generates)."

"If you enjoy watching catkins develop, search our birches and alders which soon will be in blossom. Alders are interesting because they have last year’s cones, this year’s flowers, and next year’s fruits all present at the same time. A stalk of catkins brought in now will keep your windowsill in gold for a week.”

[Re: Midsummer Flowers]: “…it’s a good time to gather common yarrow flowers for winter bouquets. Hang stems upside down in a sheltered place for a few days to let them dry thoroughly.”

[Re: Color Harvest]: "The many yellow composites of autumn make ditches glow, a sight to store away in your mind and be retrieved on a gray, sleety December day.”

[Re: In Praise of Autumn]: "As sugar maple leaves magically turn luminous pale gold, a woodland walk is an experience in radiance.”

“A bright expanse of old-field goldenrod, dotted with tawny bracken fern fronds and sun shot with scrubby scarlet staghorn sumacs, is a warming memory to recall on a snowy, sub-zero morning.”

[Re: Winter Woodlands]: "A red-headed woodpecker fills holes with acorns and other seeds, holes too deep for him or any other bird to get at. He puts bits of bark in place to seal the entrance. Later, he carefully chisels out a new door, lower down, and extracts the food.”

[Re: A Snowy Day]: “Cottontail rabbits… Isn’t it fun that prints of their hind feet are ahead of the front?”

From the birding section (posted previously):

“Nature writing of necessity involves two delightful occupations: roaming around wild places observing flora and fauna and later poring over relevant books attempting to learn more. In such pleasant ways do naturalists grope toward understanding. Questions always remain – leading to the next foray. Fortunately, the learning never ends.”

“… the nostalgic, somewhat dreamy whistle of an unseen migrating white-throated sparrow on a misty spring morning, a sound that sets blood a stirring in birdwatchers everywhere.”

“…when the flute-like ee oh lay of the wood thrush sounds through the woods, I drop everything to treasure each crystalline note.”

“One of the most astonishing all-time banding records is that of an Arctic tern found dead on the same Maine island where he had been banded thirty-four years earlier. At 25,000 migratory miles flown in a year, this tern weighing four ounces flew 850,000 in its lifetime.”

“A white-throated sparrow, that bird of haunting, ethereal whistles…”

[Ah, yes, my favorite quote of all time from any author]: "...pale satiny yellow breasts and dark velvety smudges around eyes are apparent." [I'm basking in the beauty of the image this evokes... of Cedar Waxwings!].

“In winter, tough, scaly fringes grow on toe edges of the feet of ruffed grouse, serving as unique snow shoes. These drop off in spring…. Like willow ptarmigan, these grouse will spend cold winter nights in a snow bank.”

“A family of barred owls lived near me and one often hooted from the big pine just outside my bedroom window. It was a scary but delightful experience to be wakened by that call of the wild just ten feet from my bed.”

[Re: barred owls]: “Invisible ears are cavities in lower sides of the head covered with loose-ribbed feathers that can spread to form funnels.”

[Re: Ruby-Throated Hummingbird]: “… when a thumb-sized ruby-throated leaves for South America in fall, this wee being makes an extraordinary 500-mile nonstop flight across the Gulf of Mexico from the tip of Florida to the coast of Yucatan. Miracle? Yes.”

[Re: Blue Jays]: “When they do migrate, they move by day. On April28, 1981, 2,210 were observed flying eastward along the Lake Michigan shore east of Gary, Indiana.”

[Re: Blue Jays]: “Edward H. Forbush tells of jays not only feeding and guarding an old, partly blind jay, but also leading it to water. Who would have expected compassion from this often aggressive intruder?”

[Re: Black-Capped Chickadees]: In cold weather they become totally round, fluffing feathers to almost twice their normal size, thereby trapping air as insulation. One morning at twenty-five degrees below zero, I saw inflated chickadees covered with hoarfrost crystals, dazzling in the sunlight.”

[Re: Cedar Waxwings]: “Sometimes wing tips contain a bright red wax-like substance visible only at close range. The function of those waxy droplets is unknown.”