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WHAT IS A WINTER ANNUAL? Winter annuals germinate in the fall, overwinter, and produce seeds in early spring and summer. Dandelions are also very evident in early Spring, but dandelions are perennial plants and will survive the winter and green up again in the spring. Dandelion and winter annual seeds germinate, and seedlings grow in late summer and thus are vulnerable to a fall herbicide application. For more information on winter annuals, see my article entitled “Obnoxious Lawn Weeds“.
P.S. Some of the winter annuals are often confused. Henbit (Lamium amplexicale) and Purple Deadnettle (Lamium purpurea) are similar, since they are both in the mint family. One easy characteristic difference is the shape of their leaves; Deadnettle leaves are more pointed and are a purplish-green, and Henbit leaves are more circular with rounded teeth. Field Pennycress (Thlaspi arvense) has flat, rounded seed pods, with a notch at the top; whereas Shepherd's Purse (Capsella bursa-pastoris) seed pods are more heart-shaped.
P.S.S. Catchweed Bedstraw, (syn. Cleavers; Galium aparine) is a common annual weed usually found along edges of flower beds. The species name “aparine” comes from the Latin wood meaning “to seize", which is appropriate considering its clinging nature. On hikes, our kids growing up would torment each other by mischievously, and sometimes secretively, throwing the sticky Cleavers on each other.