Cerastium brachypetalum Pers.

Gray Mouse-ear Chickweed

Cerastium brachypetalum plant2

Family - Caryophyllaceae

Habit - Annual forb.

Stems - Ascending to erect, to 35 cm, usually branched toward the tip, pubescent with long, silvery hairs, these sometimes mixed with or replaced by glandular hairs toward the tip.

Cerastium brachypetalum stem2Stems and nodes.

Leaves - Opposite, simple, entire, sessile, lacking axillary clusters of leaves. Leaf blades 0.5-2.5 cm long, spatulate (some basal leaves) or elliptic to ovate, angled to a bluntly or sharply pointed tip.

Cerastium brachypetalum leaf1Leaf adaxial.

Cerastium brachypetalum leaf2Leaf abaxial.

Cerastium brachypetalum leavesPressed leaves.

Inflorescence - Flowers in open panicles, the stalks 0.6-1.6 cm long, these usually 2-3 times as long as the sepals, erect or spreading, at fruiting sometimes appearing hooked near the tip, densely pubescent with glandular hairs, the bracts with herbaceous, green margins.

Cerastium brachypetalum inflorescence2Inflorescence structure.

Flowers - Sepals 5, 3-5 mm long, lanceolate, green, usually with membranous margins, angled to a bluntly or sharply pointed tip, densely pubescent with nonglandular and sometimes also glandular hairs, these extending past and somewhat obscuring the sepal tips. Petals 5, 2.0-3.5 mm long, about 2/3-3/4 as long as the sepals, shallowly 2-lobed at the tip, the veins usually not apparent. Stamens 10. Styles 5.

Cerastium brachypetalum sepals2Calyces.

Cerastium brachypetalum flowerFlower.

Fruits - Cylindrical capsules, 6.0-8.5 mm long, about 1.5 times as long as the sepals, slightly curved. Seeds 0.4-0.5 mm wide, the surface tuberculate, light brown.

Cerastium brachypetalum fruitFruit and pedicel.

Cerastium brachypetalum fruit2Fruit.

Flowering - March - May.

Habitat - Lawns, fields, pastures, roadsides, railroads, glades, prairies.

Origin - Native to Europe.

Lookalikes - Several other species of Cerastium, and to a lesser extent, Stellaria. Differentiation requires attention to fine details.

Other info. - To judge from collection data, this species is less common in Missouri than some other members of the genus. Currently, the majority of collections are from the southwestern portion of the state, with a few sprinkled records in the east. The U.S. distribution is similarly scattered and sporadic, mostly in the southeastern quadrant of the country. Since the plant is weedy in appearance and generally inconspicuous, it may be substantially undercollected. The species is recognized by long, silvery hairs on many parts of the plants, inflorescence bracts which are entirely green, and the open, uncrowded inflorescences. When growing in sunny areas, the plant typically has a distinct grayish appearance. In shady areas, the grayish appearance is mostly absent.

Many species of Cerastium look alike and can be difficult to differentiate. One key character important for identification is whether the uppermost inflorescence bracts have thin, translucent margins. A common error is to mistake the flower sepals for the bracts. Since nearly all Cerastium species have translucent sepal margins, this will often lead to a mistaken identification. In C brachypetalum, the bracts are green and herbaceous throughout, whereas the sepals, as in most Cerastiums, have papery margins. See the diagram below. Other characters important for identification include hair length and glandularity, and the length of the fruit stalks. Often, both flowers and fruits must be examined for a confident identification. Fortunately, populations of Cerastium will frequently have both present.

Cerastium brachypetalum sepals

Photographs taken off Lee Rd 10, Lee County, AL., 3-20-06 and 3-22-06 (DETenaglia); also at Danville Conservation Area, Montgomery County, MO, 5-8-2018 (SRTurner).


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