The genus Digitaria, commonly known as crabgrass, is a group of annual grasses found across the globe, frequently considered a nuisance in cultivated landscapes. Despite its reputation as a common lawn weed, certain varieties have a history of consumption, particularly as a grain crop in parts of Europe, Asia, and Africa. The plant’s seeds and young leaves are the edible parts, confirming that specific species are safe for human consumption. However, given its prevalence in areas often treated with chemicals, accurate identification and careful sourcing are necessary before harvesting.
Identifying Edible Crabgrass Varieties
Positive identification begins with recognizing the two most common species: Digitaria sanguinalis (large crabgrass) and Digitaria ischaemum (smooth crabgrass). Large crabgrass, the generally preferred edible variety, is distinguished by its size and prominent hairiness. Its leaf sheaths and blades feature stiff, perpendicular hairs, forming a sprawling, coarser clump than its smooth counterpart.
Smooth crabgrass is smaller and lacks dense hair coverage on its sheath and leaf blades, possessing hairs only near the base of the leaf. Both species feature a membranous ligule at the junction of the leaf blade and sheath. They grow in a characteristic prostrate pattern from a central point, resembling crab legs. The primary edible component is the seed, produced on spikelets that radiate outward from the stem, typically in clusters of three to five.
Safety Considerations and Proper Harvesting
The greatest safety risk associated with consuming crabgrass is external contamination, primarily from herbicides and pesticides. Crabgrass thrives in environments frequently treated with chemicals designed to eliminate it, such as lawns and roadsides. It is necessary to avoid any plant that has been sprayed or is near a chemically maintained area. Even pre-emergent herbicides can leave residues on the soil and plant matter. Therefore, only plants foraged from untreated, organic environments should be considered safe.
Harvesting techniques vary depending on the desired plant part. Young, tender leaves can be gathered throughout the growing season, similar to other cooked greens. The seeds, which are the main grain harvest, are typically collected in late summer or fall after maturing, often after the first frost. Harvesting the small seeds is time-consuming and must be done by hand, as crabgrass produces grain continuously rather than all at once. Some individuals may experience digestive issues due to the high fiber content, and caution is suggested for those with grass allergies due to potential pollen sensitivity.
Preparing Crabgrass for Consumption
The two main edible parts, the leaves and the seeds, require distinct preparation methods.
Preparing Leaves
Young crabgrass leaves can be treated similarly to spinach or other cooked greens. Simple processing improves texture and palatability. Boiling or steaming the leaves briefly helps to soften the structure and reduces potential bitterness. The cooked greens can then be used in stir-fries, soups, or served as a side dish.
Preparing Seeds
Preparing the seeds for use as a grain is a complex process involving multiple steps to separate the tiny edible kernel from its tough outer hull. After collection, the seeds must be threshed to remove them from the seed heads and then winnowed to separate the chaff. Traditional husking methods are labor-intensive, involving pounding the seeds in a mortar, sometimes with fine sand, to break the tough hull.
Once husked, the grain can be cooked whole like rice or couscous, or toasted before being ground into flour. Toasted seeds are often used to make porridge, lending a mildly nutty flavor. The resulting flour can be used as a gluten-free alternative in baking, similar to rice flour.
Nutritional Components
The seeds of crabgrass, historically utilized as a grain, offer a notable nutritional profile comparable to common cereals. The seeds provide a good source of protein, with crude protein levels often measured between 8 and 14%, sometimes reaching up to 15.6% in the vegetative stage. This protein content, combined with high total digestible nutrients, contributes to its value as a food source.
The grain is naturally gluten-free, making it suitable for individuals with gluten sensitivities. The leaves and stems offer significant dietary fiber, promoting digestive health. While nutritional content can fluctuate based on soil fertility and maturity, crabgrass provides essential minerals and vitamins, solidifying its place as a viable, nutrient-dense grain and green.