Global description
Stellaria media is a hairy herbaceous plant, delicate light green in colour. It can form a dense clump. Its roots are fibrous, not very deep. Stems are round, diffuse and numerous. They are erect or prostrate, emitting roots at the nodes of the base. They bear over their entire length a row of bristles, alternating at each node. The leaves are arranged in opposed pairs at each node. They ended in a sharp point. They are smooth or hairy at the base. The lower leaves are carried by a rather long petiole. The flowers are small, dull white, with 5 petals deeply divided. They are numerous and gather in slightly dense groups at the top of the branches. The fruit is dry. It is cone shaped and opens at maturity in five parts.
Cotyledons
Cotyledons ovoid, lanceolate, pointed, 15 mm long and 3.5 mm wide. Petiole as long as the blade, with a row of bristles on the upper surface.
First leaves
First leaves, simple and opposing, are carried by a petiole with a row of bristles on the upper side. The lamina is rounded ovoid, acuminate at the apex.
General habit
Fragile herbaceous plant with erect or spread growth habit, 20 to 60 cm high. It has a pubescent line along the axes.
Underground system
The root is a taproot, quickly branched into slightly deep fibrous roots.
Stem
Stem is cylindrical, hollow, diffused, abundantly branched from the base, prostrate or ascending, with a row of bristle on one side, alternating from one node to another. 20 to 80 cm long.
Leaf
Simple, opposite leaves. The lower leaves are long-stalked (5-15 mm), more or less glabrous. The lamina is oval elliptical, 6 to 40 mm long and 3 to 20 mm wide. The apex is acute, the base is wide or attenuated into a petiole. The margin is whole and both sides are glabrous. The upper leaves are narrower, with shorter or sessile petiole.
Inflorescence
Inflorescences in terminal cymes or loose axillary or solitary flowers at the axils of upper leaves, carried by a fragile pedicel. Lanceolate herbaceous bracts at the base of cymes.
Flower
The calyx consists of 5 free sepals, oblong to lanceolate, glabrous or with glandular hairs, 3.5 to 5 mm long. The corolla has 5 white free petals, much shorter than the calyx, deeply bifid nearly to the base (like 10 petals). The stamens are 3 to 5 in number. ovoid The ovary is surmounted by 3 very short styles.
Fruit
The fruit is an ovoid capsule, dehiscent, slightly exceeding the calyx, opening with 5 to 6 valves containing several seeds.
Seed
Seed substantially lenticular, 0.8 to 1.5 mm in diameter and dark brown in color. The seed coat is covered with warty circular lines.