Digitaria

Large-crabgrass-11258-seedhead2

Digitaria is a genus of plants in the family Poaceae (grasses), native to tropical and warm temperate regions of the world. Commonly referred to as crabgrass, finger-grass, or fonio, these plants are notable for their prolific seeding and are considered both valuable forage crops and troublesome weeds. The genus was first described by Carl Linnaeus in 1753, and its name is derived from the Latin for "finger", due to the characteristic shape of the inflorescences, which resemble fingers.

Description

Digitaria species are annual or perennial grasses. They have slender, erect or prostrate stems, with flat or folded leaves arranged alternately along the stem. The inflorescences are typically composed of multiple spikelets, each resembling a small finger, hence the name. The seeds of Digitaria are small but numerous, facilitating their spread across large areas in suitable climates.

Ecology

Digitaria species are adaptable and can thrive in a variety of soil types, although they prefer warm, moist conditions. They are often found in disturbed sites, agricultural lands, and urban areas, where they can quickly become dominant, outcompeting native vegetation and crops. Some species, such as Digitaria sanguinalis (large crabgrass) and Digitaria ciliaris (southern crabgrass), are particularly aggressive invaders.

Economic Importance

While many species of Digitaria are considered weeds, some are cultivated for their grains. Digitaria exilis (white fonio) and Digitaria iburua (black fonio) are important cereal crops in parts of Africa, known for their nutritional value and gluten-free seeds. These species are drought-resistant and can grow in poor soils, making them valuable resources for food security in challenging environments.

Management

The management of Digitaria species depends on their role as either crops or weeds. In agricultural settings, control methods may include mechanical removal, the use of herbicides, and the cultivation of competitive crops. For species valued as food sources, cultivation practices focus on maximizing yield through proper spacing, the use of fertilizers, and water management.

Species

There are over 200 species in the Digitaria genus, including:

• Digitaria ciliaris (southern crabgrass)
• Digitaria sanguinalis (large crabgrass)
• Digitaria exilis (white fonio)
• Digitaria iburua (black fonio)
• Digitaria ischaemum (smooth crabgrass)

Conservation

While many Digitaria species are widespread and abundant, their habitats are subject to the same environmental pressures affecting biodiversity globally. Conservation efforts for the genus focus on sustainable agricultural practices and the preservation of wild species, particularly those with potential as future food crops.