Flower:

Open cluster of 1 to 20 flowers on finely hairy stalks. Flowers are large and conspicuous compared to other chickweeds, about ½ inch across, the 5 white petals deeply notched into 2 rounded lobes with grayish streaks and yellowish at the throat. In the center are 10 stamens and 5 styles on the ovary.

The 5 narrow lance-elliptic sepals are 1/3 to half as long as the petals. At flowering time, flower stalks are erect to ascending and half as long to a little longer than the sepals, elongating and becoming more spreading in fruit. Sepals and stalks are covered in a mix of glandular and non-glandular hairs.

Leaves and stems:

Leaves are opposite, lance-linear but sometimes more oval, ¾ to 2¾ inches long and 1/8 to ½ inch wide, toothless and stalkless, the lower leaves often with tufts of smaller leaves in the axils. Stems often matted at the base with one or more upright stems terminating in an open flower cluster. Surfaces of stems and leaves can be smooth but more often densely covered with fine short hairs, often glandular especially in the upper plant.

Fruit:

Fruit is a narrowly cylindric, slightly curved capsule ¼ to ½ inch long, longer than the sepals, with 10 minute teeth around the tip. Inside are golden brown seeds less than 1 mm long.

Notes:

Two subspecies of Cerastium arvense are found in Minnesota that look nearly identical. Subspecies strictum is native and is characterized by: a taproot or short rhizomes that form a clump of flowering stems rarely over 8 inches tall, glandular hairs, and petals that stay white when dried. The other subspecies is arvense, a non-native that is strongly rhizomatous (spreading underground stems), with flowering stems up to 12 inches long, the absence of glandular hairs except in the flower cluster, and petals that turn brown when dried.