It is a Lamb's quarters / white goosefoot.

Scientific name: Chenopodium album.

A fast-growing annual herb that at maturity commonly reaches 30–150 cm tall, with an upright, branching, often slightly ridged green stem that may show pale or reddish streaking. Leaves are alternate on slender petioles and highly variable in shape: lower leaves are often broadly diamond-shaped to triangular or goosefoot-shaped, while upper leaves may be narrower and more lance-shaped. Leaf margins are irregularly toothed, lobed, or wavy, and the surface is dull green to bluish gray-green, often with a whitish, mealy or powdery coating, especially on young leaves and growing tips. Mature plants produce many small, inconspicuous greenish flowers clustered densely in branched spikes or panicles at the stem tips and leaf axils. The tiny seeds are dark, rounded, and numerous..

Lamb's quarters is edible and closely related to quinoa; its young leaves have been eaten as a spinach-like green in many cultures, though they should be consumed in moderation because they can accumulate oxalates and nitrates..

The plant shows several features typical of lamb's quarters: bluish green, slightly mealy-looking foliage; alternate leaves; variable triangular to diamond-shaped leaf blades; and irregularly wavy or toothed margins. The young leaves near the center appear pale and powdery, a common trait of Chenopodium species. The rocky disturbed setting also fits, as lamb's quarters is a common pioneer weed in gardens, cracks, walls, and disturbed soils. Because no flowers or seeds are visible, the identification is somewhat tentative; related goosefoots and oraches can look similar when young.