Flower:

Open cluster of 3 to 20+ flowers, usually in groups of 3 flowers at the tips of forked branches and arising from the uppermost leaf axils. Flowers are about ¼ inch across, the 5 white petals notched ¼ to 1/3 their length into 2 rounded lobes. In the center are 10 stamens and 5 styles on the ovary.

The 5 sepals are 1/3 as long to slightly longer than the petals, lance shaped with spreading glandular hairs on the outer surface, the outer sepals solid green and the inner with obvious white edging. Flower stalks are also glandular hairy; at flowering time they are erect to ascending and 1 to 3 times as long as the sepals, becoming more spreading and elongated in fruit.

Leaves and stems:

Leaves are opposite, toothless, stalkless, pointed at the tip, and somewhat variable in shape, the lower ones oblong to narrowly spatula-shaped, up to 2½ inches long and up to about ½ inch wide, the upper leaves becoming smaller and more lance-elliptic or lance-linear. Surfaces are hairless to sparsely covered in glandular hairs, with sparse glandular hairs around the edges.

Stems are mostly erect but weak and tend to flop over, unbranched except in the flower clusters or branched from the base, and sometimes non-flowering shoots are also produced at the base. Stems are covered in glandular hairs, especially dense in the upper plant, with a few long, woolly hairs at the lower leaf nodes.

Fruit:

Fruit is a slightly curved, narrowly cylindric capsule, up to about ½ inch long, 2 to 3 times as long as the sepals at maturity, with 10 teeth around the tip. Inside are golden brown seeds less than 1mm long. As fruit matures, the flower stalk elongates to about 5 times as long as the sepals (2 to 3 times as long as the mature capsule), tends to form a 90° angle with the stem, and aburptly angles down just below the fruit so the fruit nods.

Notes:

This was a long-time perplexing plant for us. We had heard anecdotal accounts from others about how common it was (“I see it in gravel pits all the time”) and visited a number of sites where it had supposedly been collected but never had any success tracking it down ourselves. What we ended up finding during these explorations was always either Giant Chickweed (Myosoton aquaticum) or Mouse-ear Chickweed (Cerastium fontanum), or in the cases of rock outcrops, it was Short-stalked Chickweed (Cerastium brachypodum). We weren't even sure what to look for, since we later discovered no small number of the photos on the web seem to be mis-identified. We have suspicions that some of the herbarium records for this species may be mis-identified as well. In any case, it is certainly not common, and it was mere chance that we encountered it while exploring a degraded algific talus slope at Forestville Mystery Cave State Park. We recognized it immediately as “something different”.

Nodding Chickweed is distinguished from other Chickweeds in Minnesota by the combination of: glandular-hairy all over especially in the upper plant, lance-oblong to lance-elliptic leaves that are stalkless, the lower leaves up to 2½ inches long and to about ½ inch wide, flower stalks elongating to about 5 times the length of the sepals in fruit (at least twice as long as the mature capsule) and abruptly angled down just below the fruit, flower petals cleft less than half their length, and mature capsules 2 to 3 times as long as the sepals and slightly curved. There are 2 recognized varieties of C. nutans: var. obtectum has a limited range in the southwestern US into Mexico and has long, woolly hairs on stems and leaves; var. nutans, common throughout North America, has only a few woolly hairs around lower leaf nodes.

Nodding Chickweed is larger, more erect and lanky than Mouse-ear Chickweed, which is rarely glandular-hairy, is more densely mat-forming and sprawling, and has much smaller leaves (max ~1 inch long). Giant Chickweed has clasping, heart-shaped leaves on the lower stem, leaves are shorter and proportionately broader (about twice as long as broad), flower petals are cleft nearly to the base, and mature capsules are only about as long as the sepals. Short-stalked Chickweed is about half the size of Nodding Chickweed in most respects, and fruiting stalks are comparatively shorter, only about as long as the mature capsule or shorter, and are often bend downward rather than outward.