The Original Mystery Plant
Dr. John Nelson

Photo by Jonny Stowe

Plants known as annual species have their whole lives compressed into a single year. Annual species germinate from seed then grow as much as they can from a fibrous root system, and finally go into reproductive mode and produce a crop of seeds before drying up and withering away.

Many of the garden favorites, such as cosmos, zinnia, and marigold are annuals. The evolution of an annual life term in plants is risky because there is only one period of time to get everything done.

For an annual plant, the overriding goal is the formation of a large crop of viable seeds, which represent the next generation. Unfortunately, an untimely drought, flood, fire, or insect attack may ruin the seed crop.

Plants that live for a number of seasons, the perennial species, aren't in such a rush. If a particular growing season is not conducive to abundant seed production, that's OK. A perennial plant will grow season after season and come back from a rhizome or bulb or something similarly massive below the ground. It will have many chances to reproduce, but annuals only get one chance.

The Mystery Plant is a native annual species common over much of eastern North America. It is usually smooth and dark green with plenty of toothy leaves that are sometimes lobed up and down the stem.

Healthy, happy plants growing in optimum settings may be nearly six feet tall, but they can bloom when they are much shorter. The plants produce plenty of seeds when they start flowering from mid- summer until frost.

Another attribute of annual plant species is that they produce a relatively high number of seeds, usually equipped with some mechanism for being dispersed widely, which increases the likelihood of being established the next season.

The Mystery Plant is a member of the sunflower family, Asteraceae, and has a lot of small flowers congested into heads. The individual heads are green and barrel- shaped, wrapped around the outside by a layer of slender bracts. Each flower ultimately produces a slender, brown nutlet or achene, which is equipped with a prominent fluff of a snowy- white pappus.

Eventually, the plant will shed hundreds or thousands of little white parachutes, each one with a nutlet that contains the seed.

The Mystery Plant commonly shows up in places that have been disturbed, even slightly. Scraped places in the deep woods, including wind- caused tree throws,tip- up mounds, are a good place for it. It is even more likely to occur wherever there has been burning such as small- scale campfire sites or extensive settings of previous forest fires.

Dr. John Nelson is the curator of the USC Herbarium. To learn more about the Herbarium, call 777-8196. The department also offers free plant identification. www.herbarium.org