Catchweed Bedstraw (Galium aparine)
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Catchweed bedstraw is a winter or summer annual broadleaf plant. It usually requires a disturbance to establish and is common in gardens, yards, orchards, crop fields, and other disturbed habitats. Although it is a host for some problematic nematode species and overwintering aphids, its flowers provide a food source for some beneficial insects. Because catchweed bedstraw tangles in crops and agricultural equipment, it slows down activities such as harvesting. Its bristles attach to people’s clothing and the hair or wool of animals, aiding in its dispersal. Entanglement in sheep wool reduces value.
Cotyledons (seed leaves) are oblong to egg shaped, have slightly notched tips, and are either hairless or have tiny hairs. The cotyledon and stalk combined are about 2/5 to 1-1/5 inches (9–30 mm) long. The stem above the cotyledons is square in cross-section and the first leaf set has two somewhat unequal pairs of leaves.
Stems are square in cross-section, weak, often unbranched, have tiny down-curved prickles (seen under a lens) Mature plants reach up to 3-1/3 feet (1 m) long. Leaves whorl around the stem in groups of six to eight. Individual leaves have a rounded tip and a tapering base, range from about 3/5 to 1-2/5 inches (14–35 mm) long, have bristled tips, and tiny curved prickles on the leaf edges and midveins that, under a lens, are seen pointing toward the leaf base giving the leaves a raspy or sticky touch.
Flowers bloom from March through July. Two to nine tiny, greenish to white or yellowish, four-petaled flowers cluster on long stalks from the main stem above the leaf whorls.
Fruits have two lobes that are usually densely covered with stiff, hook-tipped hairs and look like pairs of tiny, bristly balls but sometimes are hairless. The fruits are broader than long, about 4/5 to 1/5 of an inch (2–5 mm) wide, and 1/17 to 1/8 of an inch (1.5–3 mm) long. At maturity the two-lobed fruits separate into two nutlets.
Nutlets range in shape from nearly round to kidney shaped at maturity.
Reproduces by seed.
Related or similar plants
- Field madder, Sherardia arvensis