Summer of Weeds: Stinking Lovegrass

There are so many weedy grasses that we would be remiss if we let the Summer of Weeds go by without discussing at least one of them. As obnoxious and ecologically harmful as some of these grasses can be, they are easy to ignore, simply because they are not as showy and eye-catching as other weeds. They can also be difficult to identify, particularly when they are not flowering. To the untrained and unappreciative eye, all grasses appear alike and most are fairly uninteresting.

But some of them have great common names, like Eragrostis cilianensis, commonly known as stinking lovegrass, candygrass, or stinkgrass. This plant earns the name “stink” on account of the unpleasant odor that is released through tiny glands in its foilage and flower head. Probably due to my poor sense of smell, my nose doesn’t pick it up very well, but from what I can tell it has a funky or, as Sierra put it, “musky” smell. I imagine if you were to come across a large patch of stinking lovegrass blowing in the breeze, the smell would be detectable.

stinking lovegrass (Eragrostis cilianensis)

Eragrostis cilianensis is a short (up to two feet tall) annual grass from Eurasia and Africa. It is naturalized across much of North America. It has hollow and jointed stems with flat or folded leaves. Where the leaf blade wraps around the stem (an area called the ligule) there is a tuft of fine hairs. The inflorescence is highly branched, and the branches are lined with several compact, flat florets. The appearance of the flower head is highly variable, from tight and compact to spread out and open.

Inflorescences of stinking lovegrass (Eragrostis cilianensis)

Stinking lovegrass likes sandy or gravelly, dry soils in open, regularly disturbed areas with full sun. It is very drought tolerant and thrives in hot temperatures, which is why it is unfazed growing in the cracks of sidewalks and pavement. It can grow in rich, fertile soil as well, and so it often makes an appearance in vegetable gardens, agricultural fields, and ornamental garden beds.

Stinking lovegrass growing in a crack between the pavement and the sidewalk

There are dozens of species in the genus Eragrostis, with representatives around the world. A few are native to North America, and a few others have been introduced. Provenance aside, all have the potential to be weedy. Eragrostis curvula, weeping lovegrass, is an aggresive invader in some regions. Eragrostis minor, lesser lovegrass, is similar to stinking lovegrass, not only in appearance but also in its provenance and status as a weed in North America. In Wild Urban Plants of the Northeast, Peter Del Tredici mentions two North American natives that can be weedy along roadsides and in vacant lots, sidewalk cracks, garden beds, and elsewhere: E. pectinacea (Carolina lovegrass) and E. spectabilis (purple lovegrass). Last but not least, Eragrostris tef (aslo known as teff) is a commonly cultivated cereal crop in Ethiopia and surrounding countries, the seeds of which are harvested to make injera.

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Video of the Week:

The Idaho Weed Awareness Campaign has some fun educational materials, including a few puppets, to help teach children about noxious weeds. Mortie Milfoil is a puppet who helps spread the word about the aquatic invasive, Eurasian watermilfoil (Myriophyllum spicatum). Hannah teaches kids about poison hemlock (Conium maculatum). See Hannah’s video below:

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Maize Anatomy and the Anatomy of a Maze

Commonly known as corn throughout much of North America, maize is a distinctive emblem of the harvest season. It is one of the most economically important crops in the world (the third most important cereal after rice and wheat) and has scads of uses from food to feed to fuel. The story of its domestication serves as a symbol of human ingenuity, and its plasticity in both form and utility is a remarkable example of why plants are so incredible.

The genus Zea is in the grass family (Poaceae) and consists of five species: Z. diploperennis, Z. perennis, Z. luxurians, Z. nicaraguensis, and Z. mays. Maize is the common name of Zea mays subsp. mays, which is one of four Z. mays subspecies and the only domesticated taxon in the genus. All other taxa are commonly and collectively referred to as teosintes.

The domestication of maize, apart from being an impressive feat, has long been a topic of research and a challenging story to tease apart. The current understanding is that maize was first domesticated around 9000 years ago in the Balsas River valley in southern Mexico, the main progenitor being Zea mays subsp. parviglumis. It is astonishing how drastically different in appearance teosintes are from modern day maize, but it also explains why determining the crop wild relative of maize was so difficult.

Teosinte, teosinte-maize hybrid, and maize - photo credit: wikimedia commons

Teosinte, teosinte-maize hybrid, and maize – photo credit: wikimedia commons

Teosintes and maize both have tall central stalks; however, teosintes generally have multiple lateral branches which give them a more shrubby appearance. In teosinte, each of the lateral branches and the central stalk terminate in a cluster of male flowers; female flowers are produced at the nodes along the lateral branches. In maize, male flowers are borne at the top of the central stalk, and lateral branches are replaced by short stems that terminate in female flowers. This is where the ears develop.

Ears – or clusters of fruits – are blatantly different between teosintes and maize. To start with, teosinte produces a mere 5 to 12 fruits along a short, narrow cob (flower stalk). The fruits are angular and surrounded in a hard casing. Maize cobs are considerably larger both in length and girth and are covered in as many as 500 or more fruits (or kernels), which are generally more rounded and have a softer casing. They also remain on the cob when they are ripe, compared to teosinte ears, which shatter.

Evolutionary biologist, Sean B. Carroll, writes in a New York Times article about the amazing task of “transform[ing] a grass with many inconvenient, unwanted features into a high-yielding, easily harvested food crop.” These “early cultivators had to notice among their stands of plants variants in which the nutritious kernels were at least partially exposed, or whose ears held together better, or that had more rows of kernels, and they had to selectively breed them.” Carroll explains that this “initial domestication process which produced the basic maize form” would have taken several hundred to a few thousand years. The maize that we know and love today is a much different plant than its ancestors, and it is still undergoing regular selection for traits that we find desirable.

Female inflorescence (or "ear") of Zea mays subsp. mays - photo credit: wikimedia commons

Female inflorescence (or “ear”) of Zea mays subsp. mays – photo credit: wikimedia commons

To better understand and appreciate this process, it helps to have a basic grasp of maize anatomy. Maize is an impressive grass in that it regularly reaches from 6 to 10 feet tall and sometimes much taller. It is shallow rooted, but is held up by prop or brace roots – adventitious roots that emerge near the base of the main stalk. The stalk is divided into sections called internodes, and at each node a leaf forms. Leaf sheaths wrap around the entirety of the stalk, and leaf blades are long, broad, and alternately arranged. Each leaf has a prominent midrib. The stalk terminates in a many-branched inflorescence called a tassel.

Maize Anatomy 101 - image credit: Canadian Goverment

Maize Anatomy 101 – image credit: Canadian Government

Maize is monoecious, which means that it has separate male and female flowers that occur on the same plant. The tassel is where the male flowers are located. A series of spikelets occur along both the central branch and the lateral branches of the tassel. A spikelet consists of a pair of bracts called glumes, upper and lower lemmas and paleas (which are also bracts), and two simple florets composed of prominent stamens. The tassel produces and sheds tens of thousands of pollen grains which are dispersed by wind and gravity to the female inflorescences below and to neighboring plants.

Female inflorescences (ears) occur at the top of short stems that originate from leaf axils in the midsection of the stalk. Leaves that develop along this reduced stem wrap around the ears forming the husk. Spikelets form in rows along the flower stalk (cob) within the husk. The florets of these spikelets produce long styles that extend beyond the top of the husk. This cluster of styles is known as the silk. When pollen grains land on silk stigmas, pollen tubes grow down the entire length of the silks to reach the embryo sac. Successful fertilization produces a kernel.

The kernel – or fruit – is known botanically as a caryopsis, which is the standard fruit type of the grass family. Because the fruit wall and seed are fused together so tightly, maize kernels are commonly referred to as seeds. The entire plant can be used to produce feed for animals, but it is the kernel that is generally consumed (in innumerable ways) by humans.

There is so much more to be said about maize. It’s a lot to take in. Rather than delve too much further at this point, let’s explore one of the other ways that maize is used by humans to create something that has become another feature of the fall season – the corn maze.

Entering the corn maze at The Farmstead in Meridian, Idaho

Exploring the corn maze at The Farmstead in Meridian, Idaho

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