Crabgrass

Crabgrass is a summer annual weed that thrives in bare, sunny spots and quickly invades lawns.
Digitaria spp.
Origin: Europe/ Asia
USDA Hardiness Zones: 3-10
Pros:
Fast growth – quickly fills in bare lawn spots
Heat tolerant – thrives in hot, dry conditions
Cons:
Unwanted invader – spreads aggressively in lawns and gardens
Short life cycle – reseeds rapidly before dying
David Kim