Cerastium semidecandrum

Morphological description

Annual herbaceous plant, the annual mouse-ear chickweed presents a scapose habit, that is, with an elongated floral axis generally leafless in the upper part. The height ranges from 5 to 20 cm, with erect or ascending stems, greenish-yellow in color, covered by a dense pubescence composed of short hairs, both glandular and simple, which give a sticky surface to the touch. The stems branch dichotomously, that is, they divide into two symmetrical branches, developing corymbose inflorescences.

The leaves are arranged oppositely along the stem; they have a lanceolate, elliptical, or ovate shape, with dimensions ranging from 4-8 mm in width to 6-20 mm in length. They are herbaceous in texture, with an obtuse or rounded apex, and have a pubescent indumentum, especially on the upper surface. The basal leaves tend to be wider and sometimes spatulate.

The flowers are pentamerous, with five white petals that can be entire or bilobed; in the latter case the division is minimal, about one tenth or one eighth of their length. The petals are generally shorter than the sepals, which are narrowly lanceolate or oval, 3-5 mm long, with a broad membranous (scarious) margin and an indumentum of glandular and simple hairs, especially towards the apex. The number of stamens is five, with glabrous filaments, sometimes some sterile, and very small anthers (0.25-0.5 mm). The styles are five and about 1 mm long.

The inflorescence is a loose terminal cyme, composed of 3 to 30 flowers, with peduncles 5-15 mm long, often curved at the apex and sometimes folded at fruiting, covered with glandular hairs. The bracts accompanying the flowers vary from leafy and hairy in the basal parts to almost sepal-like with scarious margins in the upper parts.

The fruit is a cylindrical or slightly curved capsule, 3.5-7 mm long, about twice the length of the calyx, with 8-10 erect and revolute teeth that open to release the seeds. The seeds are very small, light brown or yellow-brown in color, with a diameter of 0.3-0.6 mm and a finely tuberculate surface. The root system is a dense thin taproot, typical of annual plants.

Habitat and distribution

The annual mouse-ear chickweed is a cosmopolitan species, widespread in all Italian regions and in the Mediterranean basin, with an extensive presence also in other temperate areas of the world. It prefers warm and dry climates, colonizing especially arid, sandy, or gravelly soils, as well as ruderal and semi-ruderal sites, such as rocky outcrops and disturbed areas.

It typically grows from hill to moderate mountain altitudes, adapting to sunny exposures and poor, well-drained soils often calcareous or siliceous. Its ability to survive in conditions of low moisture and poor substrates makes it common in Mediterranean habitats characterized by hot and dry summers.

Flowering period

Flowering generally extends from March to May, with possible local variations linked to climate and specific environmental conditions. In the milder Mediterranean climates, the annual mouse-ear chickweed can anticipate flowering already at the end of winter, while in cooler and mountainous areas flowering is concentrated later in spring.

Ecology and pollination

The annual mouse-ear chickweed, with its small white flowers, attracts a variety of pollinating insects, particularly small hymenopterans and dipterans that feed on nectar and pollen. The flower structure, with bilobed or entire petals and numerous stamens, favors entomogamous pollination, although the plant is capable of self-fertilization in the absence of visitors.

Seed dispersal occurs mainly through the capsule which, upon opening of the teeth, releases the small tuberculate seeds that can be transported by wind or small animals. The presence of glandular and sticky hairs on the stem and peduncles may also help retain the seeds near the mother plant, facilitating local colonization.

Curiosities and traditional uses

No significant medicinal or food uses are documented for this species. The common name “peverina” probably refers to the small size and the presence of glandular hairs that can give a slight pungent or spicy sensation to the touch. The plant has no marked economic or cultural relevance but represents an interesting component of pioneer flora and typical plant communities of poor Mediterranean soils.

Etymology

The scientific name derives from Greek: the genus Cerastium comes from “κεράστης” (kerastēs), meaning “horned,” referring to the elongated and pointed shape of the fruiting capsule which resembles a horn. The specific name semidecandrum combines “hemi-” (half), “deca” (ten), and “andros” (male), highlighting the plant’s characteristic of having five stamens, that is half of the ten stamens typical of other Cerastium.

The Italian common name “peverina annuale” refers to the plant’s annual life cycle and its delicate habit, with possible references to the term “peverino” for the slightly pungent tactile sensation due to the glandular hairs.

Sources

• Prof. S. Pignatti, Flora d'Italia
• Acta Plantarum - Flora delle regioni italiane (sheet by Piera Pellizzer)
• World Flora Online (WFO)