Winter annuals are plants that germinate in the fall, grow slowly throughout the winter, bloom and produce seed in the spring, and die out over the summer. Most of our winter annuals are common weeds of lawns, roadsides, and fields. They are among the most accessible wild, herbaceous plants. No need to travel to parks, forests, or greenways to see them. They can be found throughout urban and suburban residential areas in open spaces, in gardens, in patches on lawns, and in disturbed areas. Many species bloom off and on throughout the winter in the Piedmont and Coastal Plain of North Carolina, adding sprinkles of color and patches of green to an otherwise drab time of year.
Lamium purpureum and Lamium amplexicaule
Two of the commonest winter annuals in our area are Purple Deadnettle (Lamium pupureum) and Henbit (Lamium amplexicaule), closely related members of the mint family – the Lamiaceae. Both were introduced from Europe many years ago and are now widespread throughout North America. They are easily confused with each other and have very similar hooded, long tubed, pink to purple flowers. Fortunately, the leaves are often the best way to distinguish the two.
The leaves of Purple Deadnettle have a triangular or spade shape, a long leaf stalk, and often have a purple tint, or may be completely purple. However, some plants may have purple only on the leaf stems and not on the leaves, as illustrated by the two photos below.
More typical, are purple tinged leaves, as seen in the plant below.
A closer view also shows how fuzzy many of the plants become. Notice the triangular shape of the leaves.
The deep green leaves of Henbit are kidney or fan shaped, and in mature plants, are sessile (attach directly to the stem). As the plant grows and flowers, the leaves appear as whorls, separated from each other by lengths of bare stem.
A pale and weathered specimen of Henbit is shown below, followed by a more typical, deep green plant.
This mature, flowering plant illustrates the separation of the leaf whorls. The leaves of the whorls overlap, giving the impression of a single leaf that wraps completely around the stem.
Valerianella radiata (Beaked Corn Salad), which is a native winter annual, has been blooming steadily at Falls Lake from mid January to mid February, irrespective of the temperature. The photo below was taken with the temperature at 27 degrees F.
The population of Valerianella at Falls Lake displays a wide range of development and maturity in mid winter. Below are the basal leaves of a young plant.
Developing plants often have a raggedy, scarecrow appearance.
Finally, here is a maturing plant showing the opposite, broad leaves with a wide, blunt tip. The flowers are beginning to unfold at the top of the plant.
The range and distribution of these three winter annuals helps to explain their ability to withstand harsh winter conditions. Beaked Corn Salad lives as far north as Illinois and Connecticut. Henbit and Purple Deadnettle range even farther north, to Labrador and Greenland. These plants have an incredible adaptability, spanning the hot, humid summers of the South to the long, extreme arctic winters of the North.